Starting on a repstrap

Hi all,

I'm going to be in Melbourne for the next 2 or 3 months. While I'm here I've decided to make a start on the rep(st?)rap that I've mentally toyed with for at least the last couple of years. I'm keen on buying as locally as possible for all components to keep a homebrew feel to the project, which also means I have some motivation to collect everything that can't be bought from a hardware shop before I return to more remote locales.

The plan at the moment is to build a repstrap (probably Wolfstrap-based) from a combination of disposable parts and parts which will be reused in the Prusa I'm planning to print once it's all done. I figure this way if I don't have any luck, I can still buy a set of printed parts later on and build the Prusa without too much waste.

So, on to some questions...

- In line with the local theme, it seems that ABS from Lybina is my best bet. Am I shooting myself in the foot here since I won't have a heated bed for the first iteration? If so, is there PLA available without going overseas for it?

- Electronics - Gen7 seems to be an inexpensive, minimal solution, but I keep seeing more references to RAMPS. Is there something I'm missing? Regardless, I'm not so sure of myself when it comes to etching etc. Is anyone doing Gen7+endstop kits locally?

- Timing belts, pulleys. I've seen some interstate options online (like ausxmods), but this seems like a candidate for something that might be available from a hobby shop or similar. Any suggestions?

I'm sure I'll be back with more questions, but in the meanwhile thanks for any advice on offer!

-Tom

HI Tom

> - In line with the local theme, it seems that ABS
> from Lybina is my best bet. Am I shooting myself
> in the foot here since I won't have a heated bed
> for the first iteration? If so, is there PLA
> available without going overseas for it?

ABS is OK to print but you need to think about how deadly it can be where PLA is safe and easyier to print.
I belive Lybina is planning to releace PLA but when who knows, while they ABS is great. I had some test 1.75 ABS to try and found it printered great.

> - Electronics - Gen7 seems to be an inexpensive,
> minimal solution, but I keep seeing more
> references to RAMPS. Is there something I'm
> missing? Regardless, I'm not so sure of myself
> when it comes to etching etc. Is anyone doing
> Gen7+endstop kits locally?

I'm very one sided here as I sell RAMPS here in Australia and never have tried any other control system.
Gen7 is still very much the new kid on the block and being a one peice board if you blew stepper driver chip your board is for the dumpster or unless you can replace the chip.
Ramps is an arduino based sheilded which uses plouos stepper driver boards that plug into the sheild. So if you cook the board you can quickly swap out the dead one and be back printing. RAMPS also allows you to run 2 extruders and hotends (if we ever get the software to do so) plus you can run your heated bed from it.
All in all RAMPS is a simply basic system that works and works well..

> - Timing belts, pulleys. I've seen some
> interstate options online (like ausxmods), but
> this seems like a candidate for something that
> might be available from a hobby shop or similar.
> Any suggestions?

Yes, I got my belts from Ausxmods and used a belt stripper to cut the belts in half giving me a second set of belts. but I brought Alum pullies from ebay which help improve my printer s 110% these pullies can be got from ebay for $20.00 and you should have them in a week.

Hope that helps
Auzze

Thanks for the comments Auzze.

> ABS is OK to print but you need to think about how
> deadly it can be where PLA is safe and easyier to
> print.
> I belive Lybina is planning to releace PLA but
> when who knows, while they ABS is great. I had
> some test 1.75 ABS to try and found it printered
> great.

I'm not *too* concerned about ABS fumes at this stage, but I do take your point. My big worry though was whether I can expect to print out a decent mendel (and similar sized pieces) without a heated bed, or whether the warping I hear about is going to quickly become my nemesis.


> All in all RAMPS is a simply basic system that
> works and works well..

This sort of advice is gold. I think you've probably swayed me here.


> Yes, I got my belts from Ausxmods and used a belt
> stripper to cut the belts in half giving me a
> second set of belts. but I brought Alum pullies
> from ebay which help improve my printer s 110%
> these pullies can be got from ebay for $20.00 and
> you should have them in a week.

I notice that they're selling 5mm belt by the metre for what seems like a fair price. And yeah, definitely a set of aluminium pulleys will be needed since I'm trying to avoid any RP parts first up. All the better if they improve the end reprap as well.

-T

Auzze Wrote:
> I brought Alum pullies
> from ebay which help improve my printer s 110%
> these pullies can be got from ebay for $20.00 and
> you should have them in a week.

Auzze,
Which pulleys did you get? The pulleys I got from ebay were a total disaster. The teeth on the pulleys were too thin, causing the belt to slide backwards and forwards, generating a massive backlash issue.

See also my blog for pics and more info:
http://systematictechnology.net/?p=169

Shibboleth Wrote:
-------------------------------------------------------
> Auzze,
> Which pulleys did you get? The pulleys I got from
> ebay were a total disaster. The teeth on the
> pulleys were too thin, causing the belt to slide
> backwards and forwards, generating a massive
> backlash issue.
>
> See also my blog for pics and more info:
> [systematictechnology.net]

HI..

I got these ones
[www.ebay.com]

I have been using mine for months no problems.

Auzze

> I got these ones
> [www.ebay.com]
> -Shaft-Free-Shipping-/220886360288?pt=LH_DefaultDo
> main_0&hash=item336dda60e0
>
> I have been using mine for months no problems.


Strange. That's the same pulleys that I have. There must be something different with the belt you're using.

---

___________________________________________________________________________
systematictechnology.net

I got some of those and they definitely don't work with T5 belt. The teeth are much narrower than the gaps between the teeth in the belt, so it can slide a significant fraction of a millimetre when it changes direction. I complained to the seller but he never replied.

I can't see how T5 belt can vary. The profile is completely defined by T5. Only the width and materials change.

---

[www.hydraraptor.blogspot.com]

HI..

Hmmm, I'm using this belt [ausxmods.com.au] which matches the pullies OK..

Maybe I got luky for a change...

Auzze

So things are slowly coming together.

The basic design is Wolfstrap based, and apart from bearings, smooth/threaded rod and electronics everything in the machine should be available from Bunnings/local hardware.

Arduino, steppers and controllers from littlebirdelectronics.com
RAMPS 1.4 from Auzze
Smooth and threaded rod sets and linear bearings from ozreprap.com

I tossed up over whether to buy some aluminium timing pulleys but a) that would have broken my non-local purchase rules, and b) it's sort've against the spirit of my repstrapping effort to buy a part which should be printable. Instead I went with a flat belt and vinyl pulley arrangement (à la the 1X2) for X and Y axes. My Y axis is surprisingly reliable for short prints at least. There's some definite slippage on the X axis that will need to be sorted out. I think the "pulley" and the idler need to be really parallel to get nice even forces and keep things lined up. I might just end up re-homing the axis each layer until I'm able to print some workable T5 pulleys.

The cutting board extruder is a simple direct drive. The filament drive is basically a hobbed M8 bolt, cut short, with a 5mm hole drilled down the centre for the stepper shaft. The swing-arm attachment for the idler was made out of an old paint stirrer and works surprisingly well given how weak the spring is. It works so well I'm vaguely tempted not to worry about a geared extruder, though I'm a bit worried about what that lateral force is going to do to the lifespan of the motor.

The hot end has not worked out so well. It was inspired by the all steel hot end, but using a 0.6mm MIG tip (actually closer to 0.75mm) as the nozzle. Definitely cheap to build, but really needs a lathe (which I only have access to occasionally when visiting my Dad), and a nozzle that size just isn't going to give me the level of detail needed to progress to producing my own working parts. Also it was leaking like crazy around the thread on the tip, and I broke it trying to take it apart. I'll eventually go back to trying a home-made nozzle but in the meanwhile I'll be trying one of scwerta's.

Hi Tom,

I am starting on Prusa. After about 6 weeks (I have been away a fair bit with work) I have the mechanical parts assembled. Now I am about to commence the Electronics.

Below I have listed my suppliers. I am sure there are many alternatives, but you have to start somewhere.

I bought my printed parts off Greg Frost, including a Greg Frost Extuder (purchased over internet email).
The threaded steel and bolts come from Metro bolts in Richmond (in person).
I also got a few bolts from ManFax hardware in Fitzroy.
I got the smooth stainless rod from Williamstown metals .
The motors, PCD heat bed, and extruder bearings and electronics and ATX power supply came from BilbyCNC.
I went for an Arduino Mega with RAMPS 1.4 and pololu stepper drivers. (This was a package from BilbyCNC).
Plywood base came from Bunnings.
I also bought some PLA fliament from BilbyCNC.


I am very pleased with Greg's parts. Metro bolts were very helpful and nice to deal with but the they didnt seem have some of the small bolts (more on that below).
I thought Wiiliamstown metal was a bit pricey but maybe stainless steel is quite expensive. Otherwise they were fine. They can cut steel but I did not take advantage of that service.

Bilby have been great. They rang me about the filament I ordered when they they didnt have the colour I ordering in stock and they have been very responsive with orders placed on Sunday at the post office by about Thursady. (Beats ordering stuff from China!).

With combination of Greg Frost parts and the Bilby motors it seemed that I had to cut down near every M5 bolt. I bought a packet of 30 M3 at 15mm long from the hardware shop. Most of of my bolts were these and even so I had to cut many of them down. So the lack of some of the size on the BOM that I presented to Metro didnt matter much. I probably could have got the 15mm bolts there.

I made my own hobbed bolt for the extruder with a cheap set of metric taps and dies that I had in the shed using a jig made from a bit of 25mm tubular steel. I think it looks quite nice nice but of course I havent tested it yet.

Good luck with your build and some of this information helps.

Regards

Stuart.

Thanks for the input Stuart. I did come across Bilby and they've got a good range, but OzReprap ended up being a bit cheaper on shipping. I hadn't seen any feedback on either of them elsewhere so I took a punt. They also shipped quickly (and as you say, a whole lot better than the fiasco that is international shipping) and were more than willing to help me out when I mucked up some shipping details on the order. My only complaint was that the threaded rod wasn't super straight, but I'm only using one piece for my Z axis at the moment so I don't really know how much of a problem it will be.

I will add that Jaycar are generally good for little stuff like M3x10 and M3x5 as well as small (if sometimes slightly low quality) taps and other tools.

I'm interested in your hobbing experience. I had absolutely zero luck with a hand drill and ended up doing it on the lathe. I'll need to do another one for my next iteration extruder and I'm hoping it will be possible with either hand drill or drill press.

On the upside, electronics should be pretty straightforward so it sounds like you're going to be up and printing in no time. Look forward to seeing the results!

-Tom

Hi Tom,

I have built a Wolfstrap based machine myself and decided to make everything myself if possible.
The machine works very well. I also made my own hotends, without the need for a lathe. And they work very well as well.
If you want any info on my setup/build here is my site/blog.
MyBlog

Printing ABS I think you almost certainly need a heated build plate. I made one very cheaply. Works fine.

Kind Regards
Jan