Author Topic: Homebrew engraver to 3D printer Mod  (Read 12134 times)

Offline BillTodd

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Homebrew engraver to 3D printer Mod
« on: January 24, 2016, 08:53:24 AM »
Inspired by Joules and the other guys with their 3D printers , I have decided to see if I can modify a machine I built toward the end of the last millennium into a 3D printer.

The machine was knocked up in the 80's (many many mods) from bits of an old Repro-Graphic  camera and just about anything I had laying around, with only a drill press and a x-vice.   I had initially hoped it could do light milling but it was only really capable of rather slow engraving.

I'll have to re-jig the X & Y axes : ATM they are driven by M8 screws in backlash free PTFE nuts and will be far too slow for a printer.  Although I have a length of 4mm pitch lead-screw which would be a simple fix . I think I'll just spin the motors around and use timing belts 

I'll have to build a new Z axis but I've plenty of bits that I can use .

The electronics are housed in an old 5 1/4"  external drive box  (the modules were originally  mounted in a PC AT desktop case. With great foresight, I added four stepper drivers.

I have a PC configured with LinuxCNC to drive the thing (the first version ran on DOS based DANCAM ). I think a move to an arduino based REPRAP controller would be the best option , (but are they configurable for step/mm acceleration etc. ?)

Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #1 on: January 30, 2016, 09:11:23 AM »
Not much progress (still recovering from cold/flu) .

I have powered up the LinuxCNC pc which told me it'd been 1475 days since the last update .

Needless to say LinuxCNC would not run  (download latest version ATM)  Given the long print times a stand-alone small controller may be a better option

So,

Of the many  Aduino based controllers on eBay , which would be best for me ? (It will need to be configurable for steps/mm & acceleration etc.)

Any recommendations for extruder/hot end?

Bill

Offline Joules

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Re: Homebrew engraver to 3D printer Mod
« Reply #2 on: January 30, 2016, 10:24:21 AM »
Just go straight for an E3D V6 hotend.  You could machine your own or parts of it as E3D publish the working drawings for the head, so just buy what you don't fancy making.  Extruder, buy in the pinch roller and get someone to print you the rest including the herringbone gears.  I would say go for a Ramps controller as they are so standard and tons of support online for them.  However if you fancy pushing the boat out a bit, look at the Duet controller.  I am totally blown away by this one, however they aren't a cheap option.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #3 on: January 30, 2016, 12:04:46 PM »
Thanks Joules, advice noted :-)

what sort of maximum print speed is typical? (mm/s)   swapping leadscrews would be so easy and although it would lack sufficient rapids iit might print ok (?)

linuxcnc is up and running again so I'll see what rpm I can squeeze out the motors.

Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #4 on: January 30, 2016, 04:08:44 PM »
TILT!

 I configured Axis (the linux app)  to run the motors : X and Y fine but no Z...

On investigation I found the z driverr dead and , far worse, the A driver AWOL no chip and even worse, no PIC ( i wrote  a micro step driver running in a pic micro for the z and a power chips)  . I have no idea where the code will be or even if i still have a 16C84 programmer so , game over for these electronics.

I have a cheap three axis stepper driver board which i could use for testing but it looks like I'll be buying a complete driver kit .

Bill

Offline Joules

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Re: Homebrew engraver to 3D printer Mod
« Reply #5 on: January 31, 2016, 04:36:31 AM »
50mm/s would be my idea of max speed.  On small stuff your machine should be running a lot slower than that (controlled by the software) otherwise you start to see poor results.

The speed is very much dependant on the mass you are moving and how accurately you can accelerate and decelerate it.  Any vibration will be ripple and blobs on your model.

Yeah, swop over to belts for X and Y unless you can get 3000rpm out of your stepper motors !!!
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline PK

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Re: Homebrew engraver to 3D printer Mod
« Reply #6 on: January 31, 2016, 07:36:10 PM »

Yeah, swop over to belts for X and Y unless you can get 3000rpm out of your stepper motors !!!
OK, so this is more of a party trick than a practical application.
In days of yore stepper and servo drives were expensive things, so I spent a couple of years learning how to build them. It turns out, as in all things, there are compromises to be made in tuning simple motor drives.
Here's one I tuned for max RPM.



Offline Joules

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Re: Homebrew engraver to 3D printer Mod
« Reply #7 on: February 01, 2016, 06:35:53 AM »
Wow PK, you even have rpm to spare for those rapids between print.  That should loosen up the PTFE leadscrew nuts !!!


LOL  17khz stepping per axis, so I just need to over clock my LinuxCnc box, a bit
« Last Edit: February 01, 2016, 10:19:10 AM by Joules »
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #8 on: February 01, 2016, 03:03:59 PM »

OK, so this is more of a party trick than a practical application.
In days of yore stepper and servo drives were expensive things, so I spent a couple of years learning how to build them. It turns out, as in all things, there are compromises to be made in tuning simple motor drives.


Ah-ha ! old school stepper driver (high voltage and tuned !) .
Bill

Offline PK

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Re: Homebrew engraver to 3D printer Mod
« Reply #9 on: February 01, 2016, 05:17:08 PM »
Ah-ha ! old school stepper driver (high voltage and tuned !) .
Not so high actually, an L298 can only handle 46V, I was probably running that around 32V.
Most of the 'trick' is in driving it with a very precise (low jitter) square wave. In this case an $2500 Agilent function generator.

Like I said though, not really relevant in the modern age. Drives now do step morphing, anti resonance dithering and have so much protection it takes skill to let the smoke out. 
Still, I learned a lot about power electronics over that period....

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #10 on: February 07, 2016, 04:21:55 PM »
I'm finding it difficult to find time to do this... However, I did manage to get the belt drive X axis sorted today. I'm getting about 150mm/s &  >2000mm/s/s acc reliably which I hope should be OK.

I'm stil not sure whether to go for a Aduino RAMPS controller  or to try a LinuxCNC version with the bits I have first ,  If it looks like it functions OK,  then I may splash out on a Duet board (if i can find one)

Pictures will follow later
Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #11 on: February 08, 2016, 03:51:35 PM »
OK Bodged converted the X and Y axes to belt and they're working . I've decided to swap the X&Y so the longer axis is Y so that it'll take up a narrower slot on the bench.

ATM I have the 'vice' attached where a bed will go. Somewhere (in some long forgotten place) is a 6mm ally plate that will fit the bolt holes. However....

What is the best material for the bed?  -  I have a selection of ally plate 4-12mm , some perspex ( 5 & 8mm) , a sort-of 'paxolin' fibre plate (~4mm) that maybe too flexible (would need strengtheners)  but is light and would take heat . Ultimately I want a heated glass plate for ABS .
Bill

Offline picclock

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Re: Homebrew engraver to 3D printer Mod
« Reply #12 on: February 09, 2016, 10:11:08 AM »
Hi Bill.

Have you thought of using the glass that you print on as the bed. This is what I have done (see my project log). It is clipped to the bearing carriers with bulldog clips. A clamp holds the glass and connects to the belt. Because this approach minimises weight faster print speeds and acceleration are achievable. I bought an old mirror off of gumtree for 5, which has enough glass for about 6 beds.

Best Regards

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

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #13 on: February 09, 2016, 04:23:27 PM »
Hi Pic,

Yes it will need a glass plate , but I  need to have something under it that will bolt to the two slides. Today I knocked up a piece of 1/4" MDF which looks about the right sort of thickness and is flat-ish.  If I use ally my guess it will conduct the heat away from the plate (did I see you using a cork mat as insulator?)


I've been looking at making the all new Z axis . I have a another piece of type-setter extrusion (same as the slides above) and a few bearing assemblies from old HDDs . I've made nylotron tyres for the bearings and am just in the process of CADing something together.
Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #14 on: February 11, 2016, 04:33:08 PM »
Not too much achieved today.

I managed to take the X axis slide off , cut the excess aluminium off to make it flat , ready to take the new Z axis.

I have decided to mount the Z motor on top of the Z slide so that the screw now goes down with the axis rather than sticking up in the air

Attached is a back view of the latest design idea:  The screw goes into a hole through the back of the mounting plate where it screws into a PTFE nut .  Two of the rollers are mounted on flextures which can be adjusted to close any play to the extrusion.


Still not sure what to do about extruder and hot end  ?   I may have a go at making them   . What are the panls thoughts on Bowen verses direct mounted drive?


Bill

Offline Joules

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Re: Homebrew engraver to 3D printer Mod
« Reply #15 on: February 11, 2016, 05:34:53 PM »
Bill if you just go with PLA you can pick which drive you want.  Bowden is good for speed as your head is lighter and can have better rapids.  If your wanting to print with any springy filament you want direct drive  as ooze and metering are a nighmare with Bowden.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #16 on: February 12, 2016, 06:50:07 AM »
Thanks Joules,

What sort of speed and force are required for the feed motor?

The ebay hot ends seem to use a 12v 40w heater and what they call a thermistor. Is the thermistor a pt100 typically or is it really a thermocouple?

Bill

Offline picclock

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Re: Homebrew engraver to 3D printer Mod
« Reply #17 on: February 12, 2016, 07:09:31 AM »
Hi bill

Thermistor is usually a glass bead encapsulation resistive element, typically 100k at room temperature, which reduces in value as temp increases. Upper temp limit is normally 300C. Can get head heaters for 24V.

Feed force depends on head temperature/nozzle size/extruded material type. Std 1.75mm filament feeders use 3.5:1 geared reduction driving a toothed 8mm bolt which is about another 8:1. so overall drive ratio is 26:1, driven with a 3-4Kg holding torque stepper.

Best Regards

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

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #18 on: February 12, 2016, 03:25:22 PM »
So just a generic NTC thermistor . How is it calibrated ? I've seen pictures of the control panel showing temp in  degrees F & C .


Hmmm, the force is strong in this one  - looks like I'll have to get hold of some filament and experiment .


Today I mostly made  the Z axis slide  -  turned out OK smooth motion without any play  . I have yet to drill the mounting holes and I stil have a motor plate and nut part to make .
Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #19 on: February 14, 2016, 10:47:36 AM »
Found time to make a motor bracket and mount the Z axis . It moves nicely, albeit at a slow 6mm/s .

The axiz is still too long ATM  but I want to have enough spare movement to raise the X axis to a more useful height should the printer function well ( I would just have to make a pair of new vertical arms)
Bill

Offline picclock

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Re: Homebrew engraver to 3D printer Mod
« Reply #20 on: February 17, 2016, 02:21:16 AM »
Hi Bill

Thermistor measurement is done with a lookup table. It specifies resistance and temperatures at a number of points. Between the table points the graph is assumed linear and the lookup result interpolated. Reprap wiki details this and loads of other stuff.

Try http://reprap.org/wiki/Thermistor

One of the nice things about the whole reprap thing is the freely exchanged information.

FWIW I'm not sure speed in the Z axis is terribly important. Often it may be necessary to wait between layers if making a small item to allow the plastic to harden. Small precise steps are the key here.

Best Regards

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

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #21 on: February 17, 2016, 11:09:23 AM »
Thanks PC,

I've just been designing an extruder.  dual with single motor and auto lift , no idea if it'll work but should be a laugh :-)
Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #22 on: February 20, 2016, 11:57:40 AM »
Extruders get complicated fast !
Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #23 on: March 21, 2016, 07:52:15 AM »
Quick update:

My dual extruder design will not work - had not realised the extruder motor reverses in use  :Doh:
I may as well  just buy an extruder :-(

I have configured and mounted an arduino / ramps board and have the X & Y moving and homing nicely . PSU and Z have stil to be sorted.

Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #24 on: March 25, 2016, 06:35:15 AM »
ATX supply screwed onto the back of the unit.  BUT...


ATM I have the PS_ON# &  5Vsb going to the PS_ON and 5V  on the ramps board , so the arduino is not powered until I manual enable PS_ON (short it to gnd) . 

Should I link 5V and VCC on the power-control connector to power Marlin when switched on ? (and have PS_DEFAULT_OFF defined in Config.h)  - I am a little concerned at the plethora of 5V rails being shorted together.
Bill

Offline PeterE

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Re: Homebrew engraver to 3D printer Mod
« Reply #25 on: March 25, 2016, 06:47:15 AM »
Bill,

Could you find an answer from this ATX PSU rebuild description from reprap? It helped me at least.

http://reprap.org/wiki/Choosing_a_Power_Supply_for_your_RepRap

/Peter
Always at the edge of my abilities, too often beyond ;-)

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #26 on: March 25, 2016, 11:26:42 AM »
Thanks Peter,

I've just hooked the5Vsb into the VCC pin and it now powers Marlin and allows me to power down the 12v from the menu :)

Bill

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #27 on: October 28, 2018, 04:55:12 PM »
Never let it be said I rush projects...

A belated update: 2017 I got busy with work so only got to play printers towards the end of the year. I managed to set the machine up to the point of printing , well, a mess.  I replaced my home-brew extruder with a Chinese one , only to find out the problem I was having was simply one of temperature !

The first attempts to print were bugged with Y axis problems : The Y axis slideway (PEEK on anodised ally)  kept sticking so i resolved to replace it with a rolling bearing.

October '17 I got involved with a year long project at work (still ongoing!) but finally today, I found time to mod the axis with the bag of China's best plastic rollers :

And now I have my first ever successful print  :nrocks:

It's a simple bezel for a OLED display (I chose it because it is small and ready to go)

« Last Edit: November 05, 2018, 05:03:39 AM by BillTodd »
Bill

Offline RotarySMP

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Re: Homebrew engraver to 3D printer Mod
« Reply #28 on: October 29, 2018, 03:00:12 AM »
Nice work.

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #29 on: October 29, 2018, 03:42:08 PM »
What happened??? --- calling 3d print experts

After two successful prints (one over night  - pecil holder dog from Thingyverse), the extruded filament does not want to stick [edit] extruder seems to work ok when open but clicks and seems to stall when trying to print onto initial layers

suggestions please (I'm just trying increasing the temperature a bit)

Bill
Bill

Offline efrench

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Re: Homebrew engraver to 3D printer Mod
« Reply #30 on: October 29, 2018, 10:01:21 PM »
Extruder stepper clicking means it doesn't have enough torque to push the filament through the nozzle.   You may need to clean the nozzle.  The tensioner on the extruder may not be set high enough.  The filament may be out of spec (wide spots), etc., etc.

I'd recommend printing a temperature calibration object (There are several on thingiverse).


Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #31 on: October 30, 2018, 05:01:56 AM »
Thanks. I'll swap out the nozzles later and report back  :bow:

   
edit[]  That's fixed it  :D looks like the other nozzle had a burr around the hole ,I guess that after hours of pniting the burr colapsed and blocked the jet slightly.
« Last Edit: November 10, 2018, 03:03:59 PM by BillTodd »
Bill

Offline WeldingRod

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Re: Homebrew engraver to 3D printer Mod
« Reply #32 on: October 30, 2018, 08:38:25 AM »
Yeah, clicking is losing steps or skipping the drive wheel.  Causes, in rough order:
Low temp
Clogged nozzle
Too close to bed on the first layer
Bowden tube problem

And very.least likely, exotic heat leak issues causing the filament to soften and swell in the cold part of the extruder.

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #33 on: October 30, 2018, 04:27:37 PM »
Thanks for the help guys.

I'm beginning to think that the dog print was a fluke
so far apart from the afore mentioned nozzle issue, I've had the motor pully come loose on all three axes , the nozzle leak and drop blobs of snot allover the shop and because the nozzle is a tad longer than the old one , it has engraved my building plate with a banana.

edit: but hold your breath, its just printed the four paws of another dog so fingers crossed.....
« Last Edit: November 10, 2018, 03:04:52 PM by BillTodd »
Bill

Offline ddmckee54

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Re: Homebrew engraver to 3D printer Mod
« Reply #34 on: November 01, 2018, 10:14:05 AM »
Bill:

If you are a complete Noob  to 3D printing, and it sounds like that's the case, here's a couple of suggestions that I wish I would have had when I started:

1) If you don't have Home limits installed on this thing, do it now.  Zeroing the nozzle to the bed can be enough of a pain in the Tukus under normal conditions, no reason to have to do it every print.

2) Nozzle leaks, I used to get them all the time too.  I found this method of installing the nozzle on YouTube.  With the nozzle and the heat break removed from the heater block, chase the threads with a 6mm tap.  (You don't HAVE to do this, it just makes your life a little easier.)  Install the nozzle, just finger tight - no need to wrench on it yet.  Now back the nozzle off 1 flat.  Install the heat break, all the way in until it bottoms out on the nozzle but just finger tight.  Now get out the wrench and tighten up the nozzle.  Since I started using this procedure I haven't had any nozzle leaks.

3) Zeroing the nozzle and leveling the bed.  These are VERY important to getting a GOOD first layer.  If you don't have a good first layer your odds for a successful print aren't great and they just keep going downhill.

I use a Post-It note to set my initial nozzle height, I got a boat-load of them a few years back.  With my shaky hands I can't read my own writing any more so I have to use them for something.  Anyway, set your Z-axis Home limit so that that the Post-It note will just slide between the print bed and the nozzle.  You should be able to feel the resistance as you move the paper.  I'm not going to tell you that you need the sticky part up and away from the nozzle because we ALL know that - now.  You'll need to go through this procedure EVERY time you mess with the nozzle or move the hot-end in any way.

Once you've got the initial nozzle height set in the Home position move the print head to various locations on the print bed, at least the other 3 corners, and level the print bed to the nozzle's Home position.  Check it with the Post-It note, you'll want the same resistance as you had at the Home position.  You'll either use the leveling screws, if you have them, or you'll have to shim the print bed to get it level.  This may require several iterations, check nozzle height at Home position, level bed, check nozzle height at Home position, level bed...  You get the picture.

Try a test print to see if you got the nozzle's Home position correct, you MAY have to tweak it to get it set correctly.  You'll know when you got it right, the filament will firmly adhere to the print bed.  If the nozzle is too close to the print bed the filament will smoosh out around the nozzle.  Yup, smoosh is an official 3D printing term.  The sweet spot for the correct nozzle height is really pretty narrow.  Too close and it smooshes out, you get great adhesion, but your print height will be off and you'll spend a lot of time cleaning up the flash.  Too far away and you get poor adhesion to the bed, your parts have a better chance of warping, and you might not get complete fill between the filaments of the first layer.

Long winded, but I hope this helps,
Don
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Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #35 on: November 01, 2018, 10:32:47 AM »
Thanks Don ,

yes a noob indeed, 4 successful prints, countless failures..

I've just installed and confired Marlin 1.1.9 - iwas running 1.1.0 rc3 ..

I have home switches and have just set the Z correctly . ( I keep getting 'error too far' when i set home offsets , even though the x and y are zero and Z is only 0.3 ???  0,0,0 is cntre of platform)

The bed is reasonably level , i will clock it and adjust when i take it off to add a heater.

I been chasing my tail to find a 'Thermal run away error' that turned out to be ( cross fingers) a loose PSU enable connection.

Ill try your nozzle fitting technique  My chinese extruder seems to have been threaded with a hammer!
Bill

Offline ddmckee54

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Re: Homebrew engraver to 3D printer Mod
« Reply #36 on: November 01, 2018, 12:22:23 PM »
Couple questions:

What type of filament are you printing with?  I'm using PLA, because it's less sensitive to ambient temperature changes it doesn't need a heated cabinet for the printer.  With ABS a heated cabinet is ALMOST a requirement.

What are you printing your first layer on?  I print on blue painters tape because it's so simple and I've always had good luck with it.  Others swear by the glue stick method and many others will recommend the hairspray method.

Don
Too many irons, not enough fire.

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #37 on: November 01, 2018, 02:23:58 PM »
hi Don,

printing with 1.75mm pla onto masking tape (painters tape US?) seem to stick fine if I get a good initial layer.

So far the prints are staying flat without a heated bed plate (had one lift when the temperature was too high-215C)

I'll have to fix the nozzle leak before I can do anymore, just trying to summon the will to go out into the cold/wet garage to get the necessary Allan key.

Bill
Bill

Offline WeldingRod

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Re: Homebrew engraver to 3D printer Mod
« Reply #38 on: November 01, 2018, 03:51:18 PM »
Two... make three-ish tips:
Support your bed at three (and ONLY) three points on stiff springs.  Use a screw to push the bed down onto the spring.  This makes the bed angle easy to adjust and provides some "oops" compliance.  Bonus points: use long socket flat head screws!

Put a dial indicator or test indicator on your head, and use that to set the bed.  Use the screws above.

Heat your hot end to temperature before final nip-up.  You usually have three, thermally mis-matched materials in there: Aluminum, brass, and stainless.  Thread load varies a LOT with temperature.  It would help if folks used brass heater blocks, but nobody does.

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #39 on: November 04, 2018, 05:07:04 PM »
OK levelled the bed , but may need to make something stiffer / flatter later.

I'm getting problems with larger prints lifting , pulling the tape up or just not sticking

Need to solve this as I have a cunning plan....

[edit] odd this should be an animated gif (mod's any reason the uploads no longer work??)
Bill

Offline AdeV

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Re: Homebrew engraver to 3D printer Mod
« Reply #40 on: November 04, 2018, 05:56:06 PM »
Hmm, it looks like a steampunk time machine?  :scratch:

 :)
Cheers!
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Re: Homebrew engraver to 3D printer Mod
« Reply #41 on: November 05, 2018, 05:16:42 AM »
Hmm, it looks like a steampunk time machine?  :scratch:

 :)

Well, I suppose it is sortof.. It's an125 year-old steam engine design by BeuchampTower (http://www.douglas-self.com/MUSEUM/POWER/tower/tower.htm) . It was one of the first engines that I animated for Doug's site and have wanted to build one ever since. Machining one on the gear  I have would be a major problem but , with the advent of 3d printing it should be relatively easy .

Bill
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Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #42 on: November 09, 2018, 03:16:11 PM »
Added a heated bed , which seems to work ok after a bit of tinkering. 

It managed a long over night print ok (-ish, stil the odd blob of black snot from somewhere) of a de walt battery adapter.

But, two attempts printing the first part of my engine (the large circluar seperator plate) have failed after 3 hours with a 'bed thermal runaway error ' - I don't think that this is the actual problem but a consequence of power failure again  PITA!
Bill

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Re: Homebrew engraver to 3D printer Mod
« Reply #43 on: November 09, 2018, 06:25:39 PM »
aarrrggghhhh!!!!

Just tried to print the same model again, this time i got to it as it stopped - temperatures were fine , the motors were stationary while the x& y numbers on screen changed so....

Is there anything in g code that can stop the motors or swtch off the power?
Bill

Offline efrench

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Re: Homebrew engraver to 3D printer Mod
« Reply #44 on: November 10, 2018, 12:03:19 AM »
None that the slicing software would put there.

Offline AdeV

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Re: Homebrew engraver to 3D printer Mod
« Reply #45 on: November 10, 2018, 05:27:31 AM »
Does the machine have limit switches? If so, is one of those playing up?
Cheers!
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Re: Homebrew engraver to 3D printer Mod
« Reply #46 on: November 10, 2018, 07:19:03 AM »
Does the machine have limit switches? If so, is one of those playing up?

The machine has the switches from a previous life, but I don't think they're actually connected . I will check Thanks
« Last Edit: November 10, 2018, 03:07:22 PM by BillTodd »
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Re: Homebrew engraver to 3D printer Mod
« Reply #47 on: November 10, 2018, 07:23:55 AM »
None that the slicing software would put there.

Any that might getin via a bug or otherwise?  Come to think of it, would the main printing process know if the 12v rail just disappeared?   

May be I'll disconnect the PS_on signal (hard wire it on) and tey again.
Bill

Offline efrench

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Re: Homebrew engraver to 3D printer Mod
« Reply #48 on: November 10, 2018, 01:30:16 PM »
LinuxCNC gcode is pretty simple, so looking for any kind of a stop or pause code can be done with a search for "M".  If any "M"s are found, check the docs to see what it does.

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Re: Homebrew engraver to 3D printer Mod
« Reply #49 on: November 10, 2018, 02:53:21 PM »
Thanks guys,

Decided I'd spend the afternoon extending the Z range (as I need the extra height to print my engine parts)

Got a little greedy, made the extenders too long and the nozzle wouldn't reach the bed  :Doh:

Fortunately, the weather here is silly warm for the middle of November  , so was able to fix it after dark - in a T shirt in my unheated shed!.

Bill

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Re: Homebrew engraver to 3D printer Mod
« Reply #50 on: November 11, 2018, 04:19:25 PM »
Well ths is getting very frustrating!!!


Auto tuned the pid of the bed and extruder  without any problems , added the values into the config  , and up popped an update  , libraies updated some error with U8glib , now it will not compile .

Apparently u8glib has bee superceded by u8g2 but i have no idea how to add this to marlin - any arduino experts handy???

Managed to add the pid values to the installed version using m304 p i d and run bed and extruder preheat perfectly

more frustrating is that the thing is still randomly stopping while printing - it just seems to swith the power off for no obvious reason - it is not loose connection as first thought but i have no idea atm whhatnis causing it  : :scratch:
Bill

Offline AdeV

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Re: Homebrew engraver to 3D printer Mod
« Reply #51 on: November 11, 2018, 05:09:53 PM »
Just thinking out loud - does it always stop after around the same length of time running? Like an auto-power-off function, or some electronickery overheating?
Cheers!
Ade.
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Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #52 on: November 11, 2018, 05:27:47 PM »
No the stopping / power off appears random i.e it could be 3hours , 2 hours or as just now within a minute of starting to print  . I don't think it's the psu as it powers back immediately as the board is reset and it comfortably drives motors,  heater and extruder without dropping below 11.8v (measured on the board.)

I'll try running it woth bed heater as a test ...

Bill

Offline chipenter

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Re: Homebrew engraver to 3D printer Mod
« Reply #53 on: November 12, 2018, 03:00:03 AM »
The stepper drivers have thermal cut outs I fitted a computer fan , that stopped the dropped steps the board my have temperature cut outs .
Jeff

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #54 on: November 12, 2018, 05:35:33 AM »
Thanks Jeff , but all axes stop and the 12v rail disappears

I ran it last night without the hot bed and got a near perfect print (nozzle still leaking a bit). I switched to the blue painters tape as recommended by Don and it really seems to hold the print flat even without heat.

I think it must be spikes on the earth/ negative side of things . The board I have does not seem to have a separate 5v ground wire so will be reliant on the two 12v grounds which could be drawing 20+ amps peak , that's enough to cause some serious spiking/dipping of the 5v rail . 

Bill
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Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #55 on: November 13, 2018, 03:33:53 AM »
It's just completed 18 hours of printing with the bed heater disconnected ,so at least iknow the problem is caused by the heater.

Bill

Offline AdeV

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Re: Homebrew engraver to 3D printer Mod
« Reply #56 on: November 13, 2018, 03:22:10 PM »
Almost ready for a run on compressed air then!  :lol: Although that yellow is a touch bright to pass off as brass  :scratch:

Regarding the heater - the earth thing sounds like a good call; I guess the heater is thermostatically controlled on/off? Maybe when it clicks on, the current draw is occasionally enough to crash the computer... in which case, a honking great capacitor (maybe a few hundred micro Farads) across the controller's power rails would be enough to fix it.

If the heater isn't thermostatic.... back to the ole' drawing board?
Cheers!
Ade.
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Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #57 on: November 13, 2018, 06:03:09 PM »
heaters are software pid using mosfet switches  . It seems to handle full load during initial warm up so it's not as simple as voltage drop  .

I'll see if i can find time tomorrow (got my head stuck in a book this evening and now , suddenly, it's bedtime!)

One thing I discovered this morning : it is possible to refom the plastic without melting it (sort of like ironing a shirt ) using a temp controlled soldering iron at 190C or so. Enables nice smooth holes and curves.
Bill

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Re: Homebrew engraver to 3D printer Mod
« Reply #58 on: November 16, 2018, 06:44:24 PM »
Well cross fingers the extra ground wire seems to have worked.


I ran a new wire from the psu 0v to the outside of a coax power plug that connects to the arduino board .

While perusing youtube last night I found a chap talking about cooling fans for the work piece and how it improves the print. I played around with this today (while waiting, fruitlessly for E.on to fit  new smart meters) ,  and boy! does it make a difference.    just waving a small fan at the test cube straightened up the sides .

Bouyed on by this I designed and printed a fan adapter , and now I have a cube  that is 20.33 x 20.42 x 20.02  with beautiful straight sides . 

Im not sure if I can just adjust the X&Y steps per unit or whether there is a better/correct way to tweak it to size ??????


Bill
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Offline Pete49

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Re: Homebrew engraver to 3D printer Mod
« Reply #59 on: November 16, 2018, 09:55:49 PM »
Nice work Bill. I'm doing a conversion too (as if I don't have enough already) 3D printer to laser engraver as I have a spare no name one to play with. I've ordered a 500 mililwatt laser so in the meantime I looking at YouTube for inspiration.
Pete
oops..........oh no.........blast now I need to redo it

Offline efrench

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Re: Homebrew engraver to 3D printer Mod
« Reply #60 on: November 17, 2018, 03:32:49 AM »
The size is probably within normal tolerances for an FDM printer.  You need to test whether the extra material is a hardware issue or an extrusion issue.  If it's hardware related, you can use regular machining techniques to measure it.  If it's an extrusion issue, you can experiment with different settings in the slicer software or possibly in the firmware configuration file.  Have you mentioned which slicer software you're using?

My workflow is:
Design in Fusion 360.
Slice in Slic3r.
Print (Smoothieware clone).

Offline BillTodd

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Re: Homebrew engraver to 3D printer Mod
« Reply #61 on: November 17, 2018, 05:13:00 AM »
I am using Cura atm (still running xp so  choices are few) 

Thinking about the size error. It is small but it would be handy to reduce it. I feel there could be a small amount of mechanical error : the timing pulleys are plastic and belts could stretch a little . But I suspect it might be 'tracking' or the spread of the extruded filament , and thus a fixed error rather than accumulated . I'll have to print a bigger cube (or square) to find out 

Pete, your laser project sound interesting ( I've watched a couple of Marco Reps videos on youtube , where he has used a 3dprinter fitted with uv laser to make PCBs). We have a couple of laser engravers at work (and a 3kW cutter) for metal marking that use 20w scanning beams - It'll be interesting to see what your machine can do :-)
« Last Edit: November 17, 2018, 05:41:47 AM by BillTodd »
Bill