Author Topic: Anybody build Dan Gelbart angled laser centre finder?  (Read 87693 times)

Offline PekkaNF

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Anybody build Dan Gelbart angled laser centre finder?
« on: March 22, 2015, 02:31:28 PM »
VT:s lathe thread has some Dan Gelbart tutorials

One thing is sort of interesting:
     [ Invalid YouTube link ]

Laser centre finder. It is angled and a bit unusual design.

Found this one:
http://www.practicalmachinist.com/vb/deckel-maho-aciera-abene-mills/laser-centering-jig-deckel-using-dan-gelbart-s-concept-292450/

Looks like it would help me on many ocassions. Soooooooo......has anybody build it and used it?

Pekka
« Last Edit: March 22, 2015, 02:57:55 PM by dsquire »

Offline drmico60

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #1 on: March 22, 2015, 03:08:00 PM »
Hi Pekka,

I have built two versions of the device, see:

http://mikesworkshop.weebly.com/laser-centreing-device.html
http://mikesworkshop.weebly.com/laser-centring-device-mk-2.html

John Gadgetbuilder (www.gadgetbuilder.com) has also built a version.

The device works well.

Mike

RobWilson

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #2 on: March 22, 2015, 03:26:36 PM »
So he makes a lathe / grinder accurate to 1 micron ,,,,,,,,,,,, then says using  the mark one eyeball  to line things up  is very accurate  :loco:  aye right ! Bit of a builders tool  :lol: :lol:


Why not just use the good old DTI and get it spot on  :med:





Rob


Offline vtsteam

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #3 on: March 22, 2015, 05:23:21 PM »
You'd kinda have to tram pretty darn good and have real nice bearings for that projection method to work out to 5 microns, as claimed. With projection any error is multiplied by distance, and bearngs don't always wear round, nor are shafts round enough generally on a commercial machine to allow a true circular 5 micron projection tolerance. And machine vibration? Well, I dunno, maybe I'm wrong on this. What do I know -- I live in a lot cruder world!  :)
I love it when a Plan B comes together!
Steve
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Offline John Stevenson

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #4 on: March 22, 2015, 05:54:32 PM »
You also have to allow for any drafts and the workshop door being open if you are working to microns in the real world.
John Stevenson

Offline Manxmodder

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #5 on: March 22, 2015, 11:39:53 PM »
You'd kinda have to tram pretty darn good and have real nice bearings for that projection method to work out to 5 microns, as claimed. With projection any error is multiplied by distance, and bearngs don't always wear round, nor are shafts round enough generally on a commercial machine to allow a true circular 5 micron projection tolerance. And machine vibration? Well, I dunno, maybe I'm wrong on this. What do I know -- I live in a lot cruder world!  :)

Agree,now hand me the centre punch :lol:.....OZ.
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Offline PekkaNF

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #6 on: March 23, 2015, 03:51:57 AM »
Thank you all

I am aware that this concept looks very simple, but I'm pretty sure there are few snakes on this paradise too.
* usefullness must be very dependent on laser, you may want to very narrow beam. DG says focusable laser.
* I figured the bearing issue and balancing too, my main concern is actually degree of it.
* VT brought up the tramming issue.....This I didn't give attention it deserve. Although to some extent this laser angular adjustment should come handy in there.

Original paper has a mirror to deflect the beam, I was thinking of tilting the whole laser pointer. Mike &al. have done it before. I'm not getting here any points on originality.

Is there any magic on mirrors for lasers?

I'm going to read those links and think it over. I mounted ordinary laser pointer on my mill and it was very crude in near vertical and at small angle. Focus and linear distances in X/Y plane dictate whole lot. Also the piece and features of it.

VT pointed out interaction on centering and tramming....I have a knee mill and universal (in two planes) head and no drilling quill. I'm trying to found out easy method on centering and tramming (rather on one go.....).

Accuracy is not entirely futile exercise. I'm getting close finding out on my hobby when something is close enough and sometimes not even near close enough. I had some same feelings that John (MBE) about the 50 micron accuracy and stuff, but we all use units and accuracies/certaintity in pretty liberal context in out verbal communication.

Pekka

Offline John Stevenson

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #7 on: March 23, 2015, 07:02:42 AM »
To be honest I think we all have a tendency to go overboard when we can.

I do a 'lot' of bore for bearing fits which have to be good [ note, not quoting figures ]. Over the years I have bought all different types of gauges from my original 'el cheapo ' telescopic gauges to make the job easier / better / more accurate / faster [ delete as required ]

I have bore gauges with clocks , 3 point internal micrometers, internal micrometers of about three different types.
They all sit on a shelf largely unused and I still use my 'el cheapo' telescopic gauges on a day to day basis.  :thumbup:

Also in the list of "must haves but never used" ®™ are co-ax indicators [ too long to get in most places ]
Centring microscopes [ too fiddly to use after the first hour has been wasted.
And anything prefixed by *new* because engineering has been around for 200 years and nothing except electronics and materials is new. The Victorians cracked all this years ago.
John Stevenson

Offline DavidA

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #8 on: March 23, 2015, 07:07:30 AM »
Pekka,

Re Mirrors.

The astronomy people use 'optical flats' when making reflector telescopes.  These are little mirrors that have the silvered side towards the user,  as opposed to on the back and covered by a protective layer. This ensures that there is no parallax error as the beam doesn't have to pass through the thickness of the glass.
I suggest a quick look on some telescope or optical site.

Dave.

Offline PekkaNF

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #9 on: March 23, 2015, 07:48:33 AM »
John,

I share that sentiment too...I was about to buy one of those co-axial indicator but found it way too long.

Some of the tolerances and perpeticualrities and other words that borderline between obscurity and offensive are pretty damn hard to meet in many general production environment and bloody close to impossible to measure in any certainty at home work shop.

Last weekend I made (as I need a bushing between boring head and boring bar, it came "good eneough" becaue I did it without any unreasonable pursuit to perfection. Chucked scrabnium (TM) bar on lathe, took skin off, drilled 40 mm deep 6,5 mm, 14 mm and boored it close to 16mm. Then I sufaced it close to 22 mm OD (russian boring head). Tee time. Then I figured that it is way too tight inside, but light go with 16mm reamer did it and outside looked good. Took the bar on milling machine and if I had DRO I may have centered it on both axis, but because flat and cutout really does not matter here, as long as they are in about 90 decree shift I played it with an eye. Then I parted off the bush and deburred it. It did fit pretty good just by feel.

 Before I used to measure everything and neurotically and tried to get all on the same temperature and to cut last one to 0,01 mm or better - and often end up being 5,00 mm off :lol:

But sometimes it is refreshing to build something new. Just to see what is there to learn.

Pekka

Offline Arbalist

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #10 on: March 23, 2015, 08:30:13 AM »
I've seen something similar before somewhere and in spite of what's been said it looks like it would be a useful addition to my tooling. I didn't realise until seeing the video just how useful it could be to me so it looks like I'll be trying to source a suitable (focusable) laser at some point. If anyone has any more useful links please post away!

Offline Fergus OMore

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #11 on: March 23, 2015, 08:50:52 AM »
I've seen something similar before somewhere and in spite of what's been said it looks like it would be a useful addition to my tooling. I didn't realise until seeing the video just how useful it could be to me so it looks like I'll be trying to source a suitable (focusable) laser at some point. If anyone has any more useful links please post away!

Might I suggest that you read  my bit in 'All Squared away'?

Cheers

Norman

Offline Arbalist

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #12 on: March 23, 2015, 09:34:06 AM »
It's a minefield out there. Crosses, lines, dots, blue, red and green...

Is this one any good do you think?

http://www.ebay.co.uk/itm/20mW-405nm-Violet-Blue-Laser-Diode-Module-w-Driver-Focusable-2-/151235760143

Offline PekkaNF

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #13 on: March 23, 2015, 09:58:05 AM »
It's a minefield out there. Crosses, lines, dots, blue, red and green...

Is this one any good do you think?

http://www.ebay.co.uk/itm/20mW-405nm-Violet-Blue-Laser-Diode-Module-w-Driver-Focusable-2-/151235760143

It is a minefield there....If I rememeber right, human eye is more sensitive to green light than red and 5mW is considered "safe" if you blink naturally and are not sighting straight.....then again it does not show on lit room (or work lights on). 20mW sounds like could damage eyes on worst case scenario.

There are safety goggles and some goggles "improve" visibility of the laser light ray. But I'm pretty sure using safety goggle would be counter productive in this case.

Pekka

Offline vtsteam

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #14 on: March 23, 2015, 10:45:06 AM »
I didn't mean to dis the devicein the video, just question the stated tolerance. And if the real world tolerance fits my particular practical tolerance needs, then it seems like it could be be useful to make and have at some point.

Unfortuntaely all the practical details are missing -- focusing, or non focusing, safe power level, etc.

In the video, the beam looked quite wide -- but maybe it was purposely non-focused to make filming it possible.

I do realize there also are some tricks that don't actually depend on beam width (like centerng on a round, where symmetry of pattern and/or unbroken vee at the perimeter is what is being looked for) but for simple edge finding, how much can the unaided human eye resolve? Seemed like in printers we used to imagine much over 300 dpi was seen as continuous. That's about 3 thou accuity? Or is there some reason we can distinguish finer with the laser light?

Like I said, I'm not saying it wouldn't be useful a lot of times, but I'd have fairly relaxed expectations of it.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

RobWilson

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #15 on: March 23, 2015, 11:28:34 AM »
The Victorians cracked all this years ago.

Amen to that .

Here you go , no batteries  or goggles required ,,,,,,,,,,,,,,the zeroset indicator .



 

Smaller than most coaxial indicators , internal /external and parallel indicating    also handy for tramming   :coffee: 


Rob

Offline vtsteam

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #16 on: March 23, 2015, 12:01:02 PM »
Uh, that looks a lot nicer Rob than the laser clip on! :drool:  :clap:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline Arbalist

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #17 on: March 23, 2015, 01:00:51 PM »
Looking around it seems a 1mw green laser should do the job. I have a 5mw red laser and would say it's too bright. 1mw red seems to be considered safe for use but not bright enough.


Offline PekkaNF

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #18 on: March 24, 2015, 04:41:20 AM »
Ok. I ordered the red 5mW focusable laser module and it should take few weeks to surface.....

Looks like I don't want get into optical flats and collimation -yet- unless I'll find some easy reading tutorial and I absolutely needs to.

Pekka

Offline Arbalist

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #19 on: March 25, 2015, 01:21:06 AM »
Finally found the one I was thinking of the other day. Post #15 by Baron.

http://www.modelenginemaker.com/index.php?topic=4781.0

Doesn't get any easier than this does it, you could knock one up in an hour or two!  :D

Offline efrench

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #20 on: March 29, 2015, 04:15:36 AM »
The laser finder is old tech. Video camera is new tech.

Offline PekkaNF

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #21 on: March 29, 2015, 04:36:56 AM »
The laser finder is old tech. Video camera is new tech.

Would you elaborate a little further...possibly much further than using a standard webcam?

Pekka

Offline Arbalist

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #22 on: March 30, 2015, 05:25:41 AM »
He's probably not looked at the video Pekka.

Offline PekkaNF

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #23 on: April 09, 2015, 02:50:25 PM »
Got the laser modules today from the mail. Now I could do some little testing before comitting anything time consuming.

I often do 3-4 projects "inerleaved" because I'm missing tools or something and waiting stuff irks me. I need annother project to go on. Usually works fine. Now I have had a hiatus on all my projects, pretty much all week but now I startted getting most of the missing tools and parts yesterday/today.

Pekka

Offline Will_D

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Re: Anybody build Dan Gelbart angled laser centre finder?
« Reply #24 on: April 09, 2015, 04:16:30 PM »
Got a couple of lasers in the post from the 'bay  :ddb:
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