Author Topic: DRO questions  (Read 41014 times)

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
DRO questions
« on: February 18, 2011, 03:00:25 PM »
Sorry guys I have lots of daft questions

I would really like to add a digital readout to my mini mill (Axminster sieg x2)  :proj:
I have been looking at this http://www.machine-dro.co.uk/index.php?target=products&product_id=111
But I am unsure if they have scales small enough for my mill and it might cost as much as my mill  :(

My other option is the chinese scale option with remote readouts from Arc euro (very bottom of page) http://www.arceurotrade.co.uk/Catalogue/Measurement/Digital-Readouts
Does anybody use the Arc digital readouts ? do they enable fast readout from the scales ?
This might be my favourite as I can add scales as I can afford them

I also found these on ebay but can not find them in Europe http://cgi.ebay.co.uk/XYZ-3-AXIS-DIGITAL-QUILL-READOUT-DISPLAY-SCALE-DRO-SET-/300379046832?pt=LH_DefaultDomain_0&hash=item45effc83b0#ht_4693wt_907

I have the fignoogle plans but I plan to add the scales to the rear of the x axis and on the left of the y axis to keep them away from the gib adjuster and locking levers
« Last Edit: February 18, 2011, 03:02:03 PM by j45on »
Jason

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #1 on: February 18, 2011, 03:40:25 PM »
The readouts you've posted too are simply extensions of the display on Chinese type scales.

The nice thing about a 'proper' DRO is that it lets you do all sorts of nice things, PCD drilling etc.
The machine DRO system is good but only works with glass scales - so around £100 an axis, you can use magnetic scales also which are much smaller but probably nearer £160 an axis. OTOH, Chinese scales can be as little as a fiver for a modified caliper...

Another option you haven't mentioned is a Shumatech DRO. In the UK these are available from http://medw.co.uk/wiki/index.php?page=Shumatech+DRO350.
The beauty of the Shumatech is that it can read both Chinese and glass scales or a mixture of the two. The basic model is the 350, but if you're getting one from scratch you may as well consider the 550 (either the 350 with a DPU550 upgrade or a DRO550).
It's also incredibly functional and if you can be bothered you can modify the open source software (I changed it to allow fractions to be entered directly).
On my mill I use the 550 to read 3 glass and one chinese scale.

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #2 on: February 18, 2011, 04:35:23 PM »
Cheers Kwackers  :thumbup:
I forgot the Shumatech I had looked into it a bit a while ago and thought the DRO-550 was not made anymore  :scratch:

I had discounted the DRO-350 because it was the same price as a ready made unit from machine dro
which makes no sense now when I think about it as it can use cheaper scales and I enjoy building kits  :doh:

Before I go and order a DRO-350 can anyone shed any light on the availability of the DRO-550.
I am sure I read somewhere that the guy does not make them anymore ?
Jason

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #3 on: February 18, 2011, 04:58:57 PM »
The 550 is currently "out of stock", this is due to Scott not being able to obtain the processors. However I believe these are becoming available and so there should be some movement on these shortly.
Best to look on the Shumatech site for details - or better join the Yahoo Shumatech group. Worth downloading the manual and having a look anyway.

Don't discount building a 350 plus a DPU550 upgrade, the only real difference is the DRO550 can also have the LCD module attached (if you really need one). Also don't discount just using the basic 350, not quite the same features as the 550 and doesn't support as many variations of Chinese scales than the 550 but may be all you need and if you need to at some time in the future you an just add a DPU550 upgrade (plugin board that drops in place of the processor).

The DRO550 when it becomes available will need to be ordered directly from the states as its sold at cost so no point in Lester importing them.
I have 3 DRO550's, 1 on my mill, 1 on my lathe and 1 for development (I play around with writing software for it - one of my intentions when I get a bit of time is to add a basic rotary controller to it). I think its a great bit of kit and has an excellent (and expanding) feature set.
« Last Edit: February 18, 2011, 05:01:13 PM by kwackers »

Offline Bogstandard

  • Bogs Group
  • Hero Member
  • *****
  • Posts: 1107
Re: DRO questions
« Reply #4 on: February 18, 2011, 05:01:16 PM »
Jason,

I think this might be the info you are after

http://medw.co.uk/wiki/index.php?page=ShumatechEuropeanPrices


BTW, personally I would forget the scale types for low down on a mill, they are forever breaking down. I spent a fortune keeping mine going, and eventually spent so much I could have bought a top of the range glass scale type. They are OK for up on the quill.


John
If you don't try it, you will never know if you can do it.

Location - Crewe, Cheshire

Skype - bandit175

Offline NickG

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 1890
Re: DRO questions
« Reply #5 on: February 18, 2011, 05:56:29 PM »
Jason,

I had the same dilemma - I was going to go with the sliding cheapo chinese type scales but have been put off, batteries, swarf, oil ingress etc and they just aren't as accurate. So I've saved (no, well I haven't spent money) up for the glass scales and a DRO like the one in your first link.

Nick
Location: County Durham (North East England)

tumutbound

  • Guest
Re: DRO questions
« Reply #6 on: February 18, 2011, 05:57:46 PM »
I have a   DRO-350 with DPU-550 installed on my X2 mill.
Scales are the low cost Chinese ones, in my case from Shars.
I modified the scales to remove the batteries and most of the unnecessary components

FWIW, the Shumatech group has a post about a new run of DRO-550s now that the processors are available.
« Last Edit: February 18, 2011, 05:59:23 PM by tumutbound »

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #7 on: February 18, 2011, 07:47:57 PM »
Cheers for all your input guys  :beer:

Mmmm decisions decisions  :scratch:

I'm going to think about this a bit more and do some more homework and have a good measure of my mill
work out some costs and pros and cons ect ect
Jason

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #8 on: February 19, 2011, 05:34:49 AM »
I ran a 30 inch and 8 inch Chinese scale on my lathe for around 5 years with my 350 and it worked a treat.
I made covers for both and for the saddle made a 'U' shaped bracket to drive the head so that swarf and crap couldn't find it's way onto it.
Never had any problems (left the original batteries in too).

However I didn't use coolant (other than 'brushed on') so can't say how well they'd hold up but whatever the scale you need to protect it against ingress of coolant and swarf.

When I replaced my lathe I moved to glass scales. They're definitely 'better', no jitter etc. For my cross slide I used a magnetic scale which is excellent since it doesn't steal space. I'm thinking about replacing the X axis on my mill with a magnetic one, mainly because it would fit inside the casting of the bed and so I'd lose no Y movement, at the moment I lose around 1 inch with a slimline glass scale (and cover).
However using the 550 means I have a cheap Chinese scale on the quill which can be set to sum with the Z axis.

The 550 also includes edge detection and RPM reading (with suitable sensors), if you include the LCD unit it has a memory card slot which should in future be able to take a file with a list of points or operations - ideal for drilling loco side frames etc. This is work in progress though, I've been doing some stuff on it but currently am stuck for time. Not sure what other work is under way.



Offline HS93

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 788
  • Country: gb
Re: DRO questions
« Reply #9 on: February 19, 2011, 06:13:52 AM »
I ran a 30 inch and 8 inch Chinese scale on my lathe for around 5 years with my 350 and it worked a treat.
I made covers for both and for the saddle made a 'U' shaped bracket to drive the head so that swarf and crap couldn't find it's way onto it.
Never had any problems (left the original batteries in too).

However I didn't use coolant (other than 'brushed on') so can't say how well they'd hold up but whatever the scale you need to protect it against ingress of coolant and swarf.

When I replaced my lathe I moved to glass scales. They're definitely 'better', no jitter etc. For my cross slide I used a magnetic scale which is excellent since it doesn't steal space. I'm thinking about replacing the X axis on my mill with a magnetic one, mainly because it would fit inside the casting of the bed and so I'd lose no Y movement, at the moment I lose around 1 inch with a slimline glass scale (and cover).
However using the 550 means I have a cheap Chinese scale on the quill which can be set to sum with the Z axis.

The 550 also includes edge detection and RPM reading (with suitable sensors), if you include the LCD unit it has a memory card slot which should in future be able to take a file with a list of points or operations - ideal for drilling loco side frames etc. This is work in progress though, I've been doing some stuff on it but currently am stuck for time. Not sure what other work is under way.



as you have used them does swarf stick to the slides as they are magnetic? or are they very weak and cause no problemss

thanks

peter
I am usless at metalwork, Oh and cannot spell either . failure

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #10 on: February 19, 2011, 07:03:32 AM »
as you have used them does swarf stick to the slides as they are magnetic? or are they very weak and cause no problemss

thanks

peter
It does a bit, as in the magnet is strong enough to attract some of the smaller bits but not so strong they're not easily brushed off.
Ideally a small piece of felt as a wiper on the read head is all you need (something I need to do).

Offline z3t4

  • Jr. Member
  • **
  • Posts: 26
  • Country: 00
Re: DRO questions
« Reply #11 on: February 19, 2011, 10:21:50 AM »
Hi Jason

I've used Scott Shumate's DRO 350 (on an ml7 with glass scales from Allendale, who are great) and a DRO 550 with hacked caliper scales on a mill.
I wouldn't just use the caliper scales 'as-is' because they would constantly be whinging about swarf and coolant. They need to be wrapped up nice and comfy just like the glass scale heads are, so the heads need to be removed from the case and LCD, then supported in a carrier (I used Delrin) which holds it at the right separation from the scale and protects it from swarf etc. Finally the scale needs to be protected against swarf and coolant.

To keep costs down I used the replacement caliper heads from china (virtual village, < a fiver each) and Wixey tablesaw DRO tape for the caliper track, mounted on ally extrusion. The DRO 550 is an excellent bit of kit. Scott developed it as a labour of love and there was so much interest on the Yahoo group that he ended up getting a load of 4-layer SMD boards made and organised a group buy. It's not a commercial product. The deal is you get your DRO board and kit for about £150 including post and customs robbery, Scott makes nothing on it (unless you choose to leave him a donation, which I think nearly everybody did) but if the boat sinks or you fry the board or it's lost in transit, then it's your problem, not his. Some children failed to understand this.

I see on the Shumatech Yahoo group that the microprocessor that he uses is likely to be available again soon, so probably he will be ordering another group buy. If I wanted another DRO I'd be getting my name down on the group buy list.

HTH

Regards,

John

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #12 on: February 19, 2011, 02:21:08 PM »
I have had a quick add up and a DRO-350 with cables and scales ect comes to around £315.

A machine-dro read out with glass scales to fit my mini mill comes to £542 which is £100 more than my mill cost new I cant justify that for my use.

I have had an email from ShumaTech informing me that the DRO-550 is available for pre order with an estimated mid-March ship date.
Jason

Offline raynerd

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2893
  • Country: gb
    • Raynerds Projects - Raynerd.co.uk
Re: DRO questions
« Reply #13 on: February 19, 2011, 02:40:24 PM »
Jason, I have the Shumatech 350 (Kwacks old one) and although I mucked up one readout with swarf, I`ve not had any problems since covering them up. I planned a lovely plastic moulded cover but ended up with a piece of thin ally which has done the job no issues.

Just curious, if you put the X-axis readout at the back of the table, will you not lose some Y travel?  Just a thought. I`m actually interested because it does get in the way a little with the axis locking nut.

Chris

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #14 on: February 19, 2011, 02:53:20 PM »
I don't think there's a whole lot of difference in the prices of the consoles, iirc the 550 runs to around £130 if you get a pre cut box and made up cables. The basic unit without box and cables is about £80 so there's some money to be saved there if you make the cables yourself and find a suitable box.

The main advantage of the 550 is you can start with Chinese scales and upgrade to glass at any point (if ever). I also think the functionality of the 550 is somewhat better than the commercial units and currently only around 10% of the ROM is used so there's a lot of scope for extras.

I must admit to being a huge fan of DRO's. They make things so much easier...

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #15 on: February 19, 2011, 02:56:39 PM »
Chris
I was hoping to squeeze a small scale and diy aluminium cover in there on the rear of the x axis  :dremel:
I might lose 10mm of y travel but it would keep the scale away from the gib adjusters and mainly the locking screw.
Well that was my plan anyway  :lol:

EDIT I have pre ordered a DRO-550 board Thanks for the advise guys  :beer:  :nrocks:
As for scales I have not decided yet but I have a while to consider my options.
« Last Edit: February 19, 2011, 03:27:14 PM by j45on »
Jason

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #16 on: February 19, 2011, 04:23:11 PM »
Hi Jason

I've used Scott Shumate's DRO 350 (on an ml7 with glass scales from Allendale, who are great) and a DRO 550 with hacked caliper scales on a mill.
I wouldn't just use the caliper scales 'as-is' because they would constantly be whinging about swarf and coolant. They need to be wrapped up nice and comfy just like the glass scale heads are, so the heads need to be removed from the case and LCD, then supported in a carrier (I used Delrin) which holds it at the right separation from the scale and protects it from swarf etc. Finally the scale needs to be protected against swarf and coolant.

To keep costs down I used the replacement caliper heads from china (virtual village, < a fiver each) and Wixey tablesaw DRO tape for the caliper track, mounted on ally extrusion. The DRO 550 is an excellent bit of kit. Scott developed it as a labour of love and there was so much interest on the Yahoo group that he ended up getting a load of 4-layer SMD boards made and organised a group buy. It's not a commercial product. The deal is you get your DRO board and kit for about £150 including post and customs robbery, Scott makes nothing on it (unless you choose to leave him a donation, which I think nearly everybody did) but if the boat sinks or you fry the board or it's lost in transit, then it's your problem, not his. Some children failed to understand this.

I see on the Shumatech Yahoo group that the microprocessor that he uses is likely to be available again soon, so probably he will be ordering another group buy. If I wanted another DRO I'd be getting my name down on the group buy list.

HTH

Regards,

John


Hi z3t4  John
I would love to see some pictures of your scales  :worthless:
Did you get your "Wixey tablesaw DRO tape" from the UK ?
Jason

Offline picclock

  • Hero Member
  • *****
  • Posts: 613
  • Country: gb
Re: DRO questions
« Reply #17 on: February 20, 2011, 04:54:27 AM »
@zt34

>>To keep costs down I used the replacement caliper heads from china (virtual village, < a fiver each)

Do you have a link for them ?. I broke the glass on my 30" ones when something slipped  :(

Made a new one out of plastic from a cd case but would quite like to replace it.

Apart from the remote readout what other useful functions do the shumatech boards offer ?

Best Regards

picclock
Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #18 on: February 20, 2011, 06:16:59 AM »
Hi Picclock,

Probably best to have a scan of the user manual.
http://www.shumatech.com/web/products/opendro/guide

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #19 on: February 20, 2011, 07:39:05 AM »
Picclock try here http://www.virtualvillage.co.uk/callipers-and-precision-tools
they seem to be out of the cheep ones
Jason

Offline John Stevenson

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 1643
  • Nottingham, England.
Re: DRO questions
« Reply #20 on: February 20, 2011, 08:13:14 AM »
I reckon I have a spare built up DRO 350 kicking about somewhere, mumble, mumble, must have a tidy up and see if I can't find it.
Took it off a lathe and replaced it with proper commercial unit.

John S.
John Stevenson

Offline picclock

  • Hero Member
  • *****
  • Posts: 613
  • Country: gb
Re: DRO questions
« Reply #21 on: February 20, 2011, 01:39:30 PM »
@ John
That kinda begs the question as to why you replaced it ?

@j45on

http://www.virtualvillage.co.uk/300mm-lcd-display-module-for-caliper-vernier-gauge-new-001481-078.html

may work out OK. The one that's on there at the moment uses a 2032 battery (large coin cell) but I'm happy to change it to the regular style. Looks like an interesting place. Many thanks for the link.

All the Best

picclock
Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Offline John Stevenson

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 1643
  • Nottingham, England.
Re: DRO questions
« Reply #22 on: February 20, 2011, 02:03:06 PM »
The Chinese scale calipers ore useless on a lathe due to the precision and repeatability.

They have a published accuracy of 0.001" which in practice can be as much as 0.002", as a lathe measures and cuts a radius every measurement  is multiplied by two.

This also applies to errors.

So that best case of plus or minus one can soon add up to 4 thou on diameter.
If, like me you have to do loads of bearing diameters this is nowhere near good enough.
Another problem I had which others have also had is the numbers danching about making what you are reading pot luck.
They work for some, not everybody.

On a mill for home shop use they may well be all right but like most of the what was cheap options, the price differential between Chinese scales and  glass scales are getting closer.

Add to this, and it's not fully understood but 'some' of the latest import scales have a different protocol to the existing ones making them not compatible with the Shumatech and remote displays.
Don't take this as written in stone as it's too early to get a full picture whether it's just some or all and how you recognise the types.

John S.
John Stevenson

Offline raynerd

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2893
  • Country: gb
    • Raynerds Projects - Raynerd.co.uk
Re: DRO questions
« Reply #23 on: February 20, 2011, 03:18:27 PM »
Just a word of warning - I thought I`d hit the jackpot when I found the virtual village heads at £3 a replacement but the two I purchased wouldn`t link up with the shumatech!!!! The ones I got were the £4 ones that seem to be sold out at the moment.... anyone else experienced this?

Chris

EDIT--
Just read Johns post:
Quote
Add to this, and it's not fully understood but 'some' of the latest import scales have a different protocol to the existing ones making them not compatible with the Shumatech and remote displays.
Don't take this as written in stone as it's too early to get a full picture whether it's just some or all and how you recognise the types.

Glad it isn`t just me then! I thought I hadn`t wired it correctly.

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #24 on: February 20, 2011, 05:07:18 PM »
Probably worth addressing a couple of the points in Johns post above.

Protocols: The newer 550 (or the DPU upgrade for the 350) can handle most (if not all) the current protocols used.

Jitter: There were whole threads about different ways to fix this, however again the 550 (or DPU) don't suffer from this due to changes in ground layout. Because of this repeatability is higher - although accuracy remains a factor of the scale in question.

The 550 (or 350) doesn't preclude the option to run with glass scales, the beauty of them is you can combine where necessary both types.

Finally, cheap glass scales have a lot of the accuracy issues that the capacitive (Chinese) scales have. If you find cheap scales somewhere probably worth checking to see if they come with a calibration chart which will show how accurate they are for any point on the scale, I believe some of the very cheap ones don't come with any calibration - however they should still have excellent repeatability.
Worth pointing out that capacitive scales tend to be inaccurate due to price rather than some inherent problem with the technology.

However, if like me you tend to make stuff that simply 'fits' something else then absolute accuracy is less important than repeatability. I tend to machine to within a thou or so and then work with either the other part or a micrometer.
I don't think with amateur equipment its worth getting too hung up on accuracy, unless your scale is fitted to the tool point there are a myriad of ways in which accuracy can be compromised.

Offline Bogstandard

  • Bogs Group
  • Hero Member
  • *****
  • Posts: 1107
Re: DRO questions
« Reply #25 on: February 20, 2011, 06:08:07 PM »
Quote
unless your scale is fitted to the tool point there are a myriad of ways in which accuracy can be compromised.

Actually Steve, after using glass scales for the last couple of years, I can even tell when a tip requires replacing to bring me back on line to getting about 5/10ths accuracy.

I worked with vernier scales for a few years, and really struggled to keep my accuracy within a thou or two, they really are sometimes very inaccurate and obstinate. Whereas after using glass scales for so long now, hitting 1 thou accuracy could almost be done without even thinking about it, and that could be hit time after time after the machine has been allowed ten minutes to warm up.

It all depends what you are after, and in my case it was what my customers required. If I couldn't hit 5/10ths or better either way, they weren't interested.
That is all finished with now, but having got used to it, I would never go back to anything less.

With regards to the newer magnetic strip heads. I am under a personal opinion that if you are working with any sort of ferrous materials, especially cast irons and steels, you might be asking for trouble. The size of particles coming off either of these two materials can be absolutely minute, and could be attracted thru even tiny gaps where they could adhere and cause problems. As far as I am concerned, the jury is still out on those, and until they are proved to be unaffected, I would prefer to stick with the slightly longer glass scales.

But if anyone would like to donate a few of the latest Newall scales, I would certainly take them off their hands as a direct replacement for mine.


Bogs
If you don't try it, you will never know if you can do it.

Location - Crewe, Cheshire

Skype - bandit175

Offline John Hill

  • The Artful Bodger
  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2016
  • Country: nz
Re: DRO questions
« Reply #26 on: February 21, 2011, 03:25:17 AM »
I have not yet progressed to the point where I understand just exactly how DROs can be used for accurate work on a lathe.

Suppose for example I want to turn this bit of rusty steel shaft down to a diameter of 20mm. I mount the bit of steel in the lathe, touch up a suitable tool with my hone and mount it in the tool post.

How would I set the DRO, if I had one to indicate exactly 20mm when I have reduced the diameter to that? :scratch:
From the den of The Artful Bodger

Offline John Stevenson

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 1643
  • Nottingham, England.
Re: DRO questions
« Reply #27 on: February 21, 2011, 03:52:30 AM »
You take a cleanup pass and measure that, then set your DRO to that value.

John S.
John Stevenson

Offline Bogstandard

  • Bogs Group
  • Hero Member
  • *****
  • Posts: 1107
Re: DRO questions
« Reply #28 on: February 21, 2011, 04:11:43 AM »
First off John, you would take a light skim off the rusty old bar to get yourself to clean metal. Then take a micrometer reading off the bar.

Depending whether you work in imperial or metric, you press a button on the display to put you into the correct units, then press another button to zero up the display.

Also depending on how you originally set the display up, either amount off the diameter, or like most people and lathes, amount off radius (1mm off radius takes 2mm off the diameter).

You can then do what John S has said, input that figure into the display and cut until your display shows what you want to end up at.

Or do it the way I do, a**e about face.

Subtract the diameter you want to end up at, say 15mm, from the mic measurement, again say 19.5, leaving 4.5mm.

By taking your cutter display into half that figure (2.25mm) in easy stages, once you reach 2.25mm on the display, your bar should be exactly 15mm diameter.

That does sound rather complicated, but in fact, once you get used to it, everything becomes second nature and you can cut down to your 15mm size continually, time after time. In fact if you zero your tool when you reach the correct size, no matter what size bar you put in there, if you cut down until the display shows zero, you will be at 15mm diameter exactly.

There are different ways of doing things with these display boxes, each type having various features you can use, even some that will help you to turn tapers.

Depending on the type of scale that is fitted to the display, governs how accurate and repeatable the cutting action becomes. Using cheap vernier scales you would expect your accuracy to be within 0.002" (0.05mm), whereas with the more expensive glass scales, that figure can become 0.0002" (0.005mm)


John
If you don't try it, you will never know if you can do it.

Location - Crewe, Cheshire

Skype - bandit175

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #29 on: February 21, 2011, 05:12:54 AM »
It all depends what you are after, and in my case it was what my customers required. If I couldn't hit 5/10ths or better either way, they weren't interested.

Hi Bogs, your point above is what I mean. Most of us amateurs don't have customers, we also lack both decent machinery and the nounce to make do with the slightly iffy stuff that abounds.
(I've long observed that a good man can do fine work with poor tools, whilst a poor man will always benefit from good tools).

Fitting glass scales to an amateur machine and suddenly expecting 2/10ths accuracy is bound to lead to disappointment. Many machines don't allow for good placement of the scales meaning racking can be an issue and that's before you come to realise that they're not a substitute for machining skills.

There does seem to be an attitude on here that it's glass scales or nothing and that's simply not true. I survived years with cheap chinese scales and managed just fine. I think rather than be put off because people can't afford a full set of glass scales people should be encouraged to use what they can afford. Chinese scales make a lot of things so much easier even if you have to crane your neck to look at the built in display.
When I changed machines I switched to glass scales and there's no doubt they're an improvement but if I couldn't afford them then I'd have no hesitation using Chinese scales.

Offline NickG

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 1890
Re: DRO questions
« Reply #30 on: February 21, 2011, 07:57:47 AM »
The problem I have with this is, most of the stuff we do requires accuracy of a thou or so. Therefore if chinese scales still mean I need to double check everything with manual measuring tools, what's the point in spending a couple of hundred quid kitting the machine out with them? I've managed thus far with manual dials and measuring equipment so what advantage will chinese scales give me other than agro replacing batteries, swarf etc getting into them.

If you're buying chinesey ones then glass scales, you're spending even more money so why not wait until you can afford the proper ones? That's what I'm doing.

Nick
Location: County Durham (North East England)

Offline kwackers

  • Sr. Member
  • ****
  • Posts: 356
Re: DRO questions
« Reply #31 on: February 21, 2011, 08:22:33 AM »
Depends what you do with your scales...

For example - co-ordinate drilling. The tolerance of most bolt holes means a thou is neither here nor there. Chinese scales (at least the one's I've used) have decent repeatability. They suffer from thermal expansion and contraction as do glass scales (and your machine) so close fitting parts need to be machined consecutively - especially if like me you share your space with a kiln!
In practice even where accuracy is required you can quickly machine close to size with Chinese scales, for 90% of stuff though I found the accuracy fine.
You've also got to bear in mind if you're not using coolant (I don't usually) then the act of machining a part will change it's size considerably. I'm sure we've all been there, make a part that's a good fit then when it's cooled it just 'drops' through!

But yeah, if you're intending to replace the Chinky scales in a relatively short time scale there's no point.
I had Chinese scales for 5 years fitted to a fairly rubbish Chinese lathe, whilst I had that lathe I wouldn't have considered spending it's value on glass scales, in terms of accuracy they wouldn't have helped...
When I got round to upgrading my machinery I felt both it and me had progressed to a point whereby it was worth buying and fitting higher quality scales.

Offline picclock

  • Hero Member
  • *****
  • Posts: 613
  • Country: gb
Re: DRO questions
« Reply #32 on: February 21, 2011, 10:02:15 AM »
As another take on chinese scale accuracy, the tolerance of +/- 1 thou is over the length of the scale. The resolution of the scales is 0.5 thou or 0.01mm. This means that over a short distance after the scale has been zero'ed the accuracy is far better than the +/- 1 thou, and the repeatability also.

On my mill the measurement of a given point changes by 1 thou just from when its cold in the morning to when the workshop has warmed up. As this seems to occur repeatedly and consistently, I surmise that this is the machine table changing size with the temperature change.

So the chinese scales are cheap, but I think they are very accurate for the price you pay. Once fitted, no one is going to go back to counting turns on a handle with its associated backlash issues. 

I am considering fitting the scales with a full length flexible rubber(?) cover or a tube with a slot in it and using a remote readout - but so far its just one of those jobs on the tuit list.

picclock



 
Engaged in the art of turning large pieces of useful material into ever smaller pieces of (s)crap. (Ferndown, Dorset)

Offline z3t4

  • Jr. Member
  • **
  • Posts: 26
  • Country: 00
Re: DRO questions
« Reply #33 on: February 21, 2011, 01:31:17 PM »


Hi z3t4  John
I would love to see some pictures of your scales.
Did you get your "Wixey tablesaw DRO tape" from the UK ?

Hi Jason

The tape was left over from adding their digital saw fence thingy to my tablesaw. I had been impressed by the DRO 350 and it seemed to me that an experiment using this tape and the Virtual Village scale heads would be worth a punt. At a fiver each it would be rude not to. I got the heads back in May 2009, at which time they cost £3.77 each. The Chinese seem to have upped their prices for geek-food since. The tape was free but I subsequently got some more from Allendale. I think it was very cheap (2 metres for £~20, ISTR).

The issues that JohnS has mentioned were very much in evidence for the DRO 350 but part of the motivation for the DRO 550 was to address them. It is possible to read most scales but Spherosyn, Mitutoyo and some of the newer Chinese ones are, er, resistant. It may be that the firmware will be developed to read more protocols. Certainly there are some very bright people on the Yahoo group. I have not found jitter or wildly erratic display to be a problem with the new DRO.

For my part, I just love messing with this stuff. If I were depending on it to buy Jaffa cakes no doubt I would get a Spherosyn properly fitted. But then I would be working to gnat's bollock accuracy, and I don't have the skill nor the kit to do that. I am (honestly) in awe of people like JohnS and Bogs, who not only do have that skill but are willing to share it with those of us who want to learn.


This is a pic of the gutted head with an unmolested one in the background (NB anti-jitter capacitors):


This is a closer pic:


This is the tape and the extrusion, waiting to be fixed:


This is it working:


HTH,

John

edited for typos
« Last Edit: February 21, 2011, 04:39:50 PM by z3t4 »

Offline John Hill

  • The Artful Bodger
  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2016
  • Country: nz
Re: DRO questions
« Reply #34 on: February 21, 2011, 01:53:20 PM »
Thanks John S. and John Bogstandard.

OK, so the accuracy of the job depends on how accurate one is in measuring the starting diameter and if you are careful there the final size will be accurate without further measuring?  I can see that would be a great advantage but not so much if it is still necessary to make a final check with the micrometer. :coffee:


I have a simple system using Chinese scales operated by flexible cables which is great for avoiding gross errors but I still have to 'sneak up' on the final diameter.
« Last Edit: February 21, 2011, 01:55:08 PM by John Hill »
From the den of The Artful Bodger

Offline John Stevenson

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 1643
  • Nottingham, England.
Re: DRO questions
« Reply #35 on: February 21, 2011, 04:27:00 PM »
Don't get me wrong I am not knocking the Chinese Digi-callipers, I think they are marvellous and I have about 8 or 10 around the shop.
Every machine in common use 'should' have one but what happens in practice is that the most used machine has six  :scratch:

However once you know the limitations they are easy to work round, I tend to get close with the callipers, then swap to micrometers if needed, things like bearing diameters need to be spot on so it's micrometers to finish.

Tomorrow I have to make 3 long shouldered bolts with three diameters, 25mm, 22mm and a 20mm x 2.5 pitch thread, none of these diameters, lengths etc are critical and I'll use the digi-callipers for everything. No point working to tenths when not necessary, it cost money to do this and it's usually my money so that's a big incentive. :beer:

My complain with the 350 was jittering and because it was on a lathe, the accuracy. I have a Sino readout now and it works well but I still don't rely on it all the while, my main lathe a TOS 14 x 40, is now about 10 years old and still deadly accurate on the dials, if I put 0.025mm on it will remove 0.025mm from the diameter. The Sino will follow this the 350 wouldn't.
John Stevenson

Offline BillTodd

  • Hero Member
  • *****
  • Posts: 1096
  • Country: 00
  • Colchester Essex (where the lathes were made)
Re: DRO questions
« Reply #36 on: February 22, 2011, 06:24:29 AM »
Quote
The tape was free but I subsequently got some more from Allendale. I think it was very cheap (2 metres for £~20, ISTR).

John that 'tape' is exactly what I've been looking for - still am ;) I can't see it on the Allendale site, do you have a link?

Bill

[edit]

Ah ha found it  ----- out of stock ! :(  :bang:

BTW JohnS I still intend to experiment with an optical mouse or encoder based digital trava-dial, but I'll continue it here, as there'll be less chance of bumping in to an know-all/nothing idiot ;)
« Last Edit: February 22, 2011, 06:33:36 AM by BillTodd »
Bill

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #37 on: February 26, 2011, 11:45:19 AM »
Bill
they have the tape/strip here WR7003 Sensor Strip Set third item down

http://www.wixey.com/fence/spareparts/index.html
Jason

Offline John Stevenson

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 1643
  • Nottingham, England.
Re: DRO questions
« Reply #38 on: February 26, 2011, 01:42:12 PM »


BTW JohnS I still intend to experiment with an optical mouse or encoder based digital trava-dial, but I'll continue it here, as there'll be less chance of bumping in to an know-all/nothing idiot ;)

He seems to have disapeared, whatever the forum is running well now about 3 or 4 people are missing.

John S.
John Stevenson

Offline BillTodd

  • Hero Member
  • *****
  • Posts: 1096
  • Country: 00
  • Colchester Essex (where the lathes were made)
Re: DRO questions
« Reply #39 on: February 27, 2011, 10:06:33 AM »
Thanks for the link, Jason   :thumbup:
Bill

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #40 on: March 02, 2011, 02:32:44 PM »
Got some scales today and I am glad I did not order the 16" as the 12" is 17"s long and will read just over 13"s
Unfortunately I am going to have to send one of the 12" ones back as it looks like a banana  :(

Jason

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #41 on: April 17, 2011, 02:43:28 PM »
I built my DRO-550 today which came in the post last week so now I need to pull my finger out and finish adding the scales  :hammer:
I also need some scale cables is the mini din 4 pin connector the same as an s-video lead plug ?
If they are I can buy a long one from ebay and cut it in half and solder the other end to the scales  :zap:

Sorry cr*ppy camera phone picture again
This picture makes the led's look washed out,I also need to make a mounting arm :dremel:
Jason

Offline Bluechip

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 1513
  • Country: england
  • Derbyshire UK
Re: DRO questions
« Reply #42 on: April 17, 2011, 05:28:37 PM »
Jason

4-way mini-din ???


Piccy herewith:

http://uk.farnell.com/pro-signal/av00948/lead-4pin-mini-din-plg-plg-3m/dp/3712394

Fairly common item

Dave BC



I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #43 on: April 17, 2011, 05:48:04 PM »
Yes thats the one
I have just bought a s-video lead from ebay to see if it is the same 99p with free postage ,I thought it would be worth a try
looks similar http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320658616652#ht_3623wt_1032
It will probably be cr*p though
Jason

Offline andyf

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 1795
  • Country: gb
    • The Warco WM180 Lathe - Modifications
Re: DRO questions
« Reply #44 on: April 17, 2011, 06:13:22 PM »
Condensed quote from the Maplin catalogue:
"Mini-DIN plugs ... available in 4,6 and 8 pin types. The 4-pin is the standard S-VHS connector, the 6-pin is the standard PS/2 keyboard and mouse connector. "

It doesn't say what the 8-pin is used for.

You were wise to buy a made-up lead. It's bad enough soldering to a full-size DIN plug or socket; mini-DINS must be a real pain.

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #45 on: April 17, 2011, 06:21:42 PM »
Thanks Andy

Thought they looked the same and that confirms it  :thumbup:
I just hope the s-video lead has four core cable and not a pair of tiny coax cables.
Jason

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #46 on: April 21, 2011, 03:20:38 PM »
I got my 99p s-video cable today and it is a perfect fit and has four separate wires but it is very thick and inflexible so I think I will have to buy some plugs and make my own.  :zap:

I am also struggling to find out what capacitor/s to solder into the scale in place of the battery does anybody know ?
Jason

tumutbound

  • Guest
Re: DRO questions
« Reply #47 on: April 21, 2011, 09:53:38 PM »
The value of the capacitor(s) is not critical.
According to the Shumatech site, anything up to 330uF electrolytic with a .01uF ceramic in parallel.

I used a 100uF as it was the largest I could get in an SMD package.

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #48 on: April 22, 2011, 07:16:11 AM »
Cheers Tumutbound  :beer:
Kenneth  :thumbup: if I wanted to build a cable from scratch what would you recommend ?

I added some green filter today I was not happy with the colour it was a bit yellow under my shop lights
I'm happy now but I had to buy a roll just to get the bit I needed  :palm:
So I have some spare if anybody needs a bit for their dro  :thumbup:

Before


After
Jason

Offline andyf

  • In Memoriam
  • Hero Member
  • *****
  • Posts: 1795
  • Country: gb
    • The Warco WM180 Lathe - Modifications
Re: DRO questions
« Reply #49 on: April 22, 2011, 09:47:32 AM »
I got my 99p s-video cable today and it is a perfect fit and has four separate wires but it is very thick and inflexible so I think I will have to buy some plugs and make my own.  :zap:


Not that I want to discourage you, but in MEW issue 111 (Dec 05/Jan 06) there's Part 1 of a series about using chinese calipers and the Shumatech 350 readout.

The author said: "I found my 4 pin DIN plugs and sockets on the back of the DRO a nightmare to solder up. [They] just have solid pins to solder to. A type with solder buckets would have been easier with less possibility of solder bridges."

Good luck!

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline j45on

  • Sr. Member
  • ****
  • Posts: 380
  • My tiny workshop Location Ashford Kent
Re: DRO questions
« Reply #50 on: April 22, 2011, 10:44:59 AM »
Cheers Andy I shall keep that in mind  :thumbup:
I am having trouble with scales though,I have wired one up to test and it was working fine with a battery  but wont work without one :scratch:
I have a 100uF electrolytic with a .01uF ceramic in parallel as mentioned by Tumutbound


 :doh: Looks like I forgot to add some jumpers ( i wondered what they were for  :palm: )
« Last Edit: April 22, 2011, 06:51:15 PM by j45on »
Jason

tumutbound

  • Guest
Re: DRO questions
« Reply #51 on: April 22, 2011, 08:02:22 PM »

Not that I want to discourage you, but in MEW issue 111 (Dec 05/Jan 06) there's Part 1 of a series about using chinese calipers and the Shumatech 350 readout.

The author said: "I found my 4 pin DIN plugs and sockets on the back of the DRO a nightmare to solder up. [They] just have solid pins to solder to. A type with solder buckets would have been easier with less possibility of solder bridges."

I got rid of the DIN plugs and used 4 pin microphone plug/sockets similar to these.
Much easer to solder and as they screw together, no chance of scales becoming disconnected.

Offline SPiN Racing

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 506
Re: DRO questions
« Reply #52 on: June 24, 2011, 10:29:24 AM »
Gereat thread everyone. A lot of questions I had.. but hadnt formulated have been clarified, and answered.

An example.. why get the small digital chinese ones.. but now I understand much better how they work, and how the DROs work with them.


 :mmr:
SPiN Racing