Welcome! Log In Create A New Profile


problem with x idler bracket

Posted by JenbotUK 
problem with x idler bracket
November 18, 2008 09:06AM
I'm new here so apols if this question has already been answered somewhere...

I am building the idler bracket (from a bits from bytes full mechanical gold kit) and i've only been able to find this documentation


I've seen a few other parts that have PDF files with each parts listed (and the steps how to build each part). Can someone point me to this area on the site?

My issue is that I am using the above 3D drawing but am unsure about the M8 Washer and the M8 Spring Washer. Also, the pulley doesn't seem to want to go on my screw - any clues as to how to slightly widen the hole without cracking the acrylic would be much appreciated.

Cheers. J

Edited 1 time(s). Last edit at 11/18/2008 09:10AM by JenbotUK.
Re: problem with x idler bracket
November 18, 2008 09:45AM
The earliest docs (near the bottom) have assembly instructions

I found for each part, you needed to remove the blue plastic from both sides (which ends up sticking to your fingers with static) and then tidy it up with a file.
I found some small needle files of various shapes (round, D, and flat) from a local market stall.

The internal holes sometimes needed a bit of filing to make them smooth - make sure you have smooth movement of the x-carriage before you assemble the rest of the frame. it will save you time later.

The laser-cut recesses around the holes (like the ball-bearing holes) needed a bit of scraping out, particularly in the corners. There seemed to be small lumps of molten plastic that had stuck to the laser-cut surface making it rough. A couple of minutes with a needle-point file was enough to make each bearing fit properly.
Re: problem with x idler bracket
November 18, 2008 09:50AM
Hurrah! Thank you grinning smiley
Re: problem with x idler bracket
November 18, 2008 09:52AM
p.s. Be gentle when tightening the bolts. It's easy to crack the acrylic, so buy some superglue. I found that if I held the nut with my fingers I could tighten it with the allen key, but if I used pliers or a spanner it was easier to crack. This was particularly easy on the corner brackets.
YMMV :-)
Re: problem with x idler bracket
November 18, 2008 10:26AM
Okay, another problem with the x assembly...in Step 1 of the above PDF - part 6 (the carriage base part) the hole in the centre is really not cut all the way through. I have some tiny screwdrivers and am trying to cut through it but they don't seem to be doing the trick. I've already chipped a few other parts and I know that this one is critical - any more hints? Or should I try and get another one sent to me? If only I had a personal laser cutter....
Re: problem with x idler bracket
November 18, 2008 10:54AM
Many of the larger holes (and some of the smaller ones) still had the center plastic attached. Normally, I could press this out with a bit of force. a nice sharp craft knife was useful for trimming off the outer tabs, and the internal holes often needed filing.

For some reason, that paticular hole (the large bearing? hole) is not used in my completed Darwin. The extruder is attached using 4 M5 bolts through one set of the 4 holes in that plate. Perhaps it was from an earlier design? I'd be inclined to leave it as it is.

The critical holes are the ones with bearing sleeves (the ends of the x-carriage). I widened them with the file until I could put the insert in and a rod would slide easily through the hole.

Print out the laser-cut parts list - it's handy to find parts and also to see if you need the bits from the holes (some of the holes are re-used elsewhere)
Re: problem with x idler bracket
November 18, 2008 11:09AM
Great. Wow - this forum is fantastic!
Re: problem with x idler bracket
November 18, 2008 12:07PM

My trials so far are on [renoirsrants.blogspot.com]

I've just done all this so I'm happy to help others :-)

Re: problem with x idler bracket
November 19, 2008 12:49PM
I'm putting the Z Belt Tensioner together and it's not clear to me what part number 75 is (m8 Nut Half BZP). Also, I have nut number 20/8/6 but I can't see one that is between those sizes. Also, for the Z Idle pulley the nut on the end in the sketch says use number 20 - I used a number 8 and it works fine - am I using the wrong screw?

Re: problem with x idler bracket
November 19, 2008 12:57PM
A halfnut M8
(a nut about half the height of an ordinary nut)

Re: problem with x idler bracket
November 20, 2008 07:36AM
Thanks Sid.

Now a question with the x carriage assembly - when i slide the rod through the bearings, HOW smooth does it need to be? If I file the holes, then the black plastic bearing doesn't stay in the hole (did you glue it in place?). I don't want to file the black bits if I don't need to, but not sure how to make the movement of the rod through the bearing totally smooth.

Re: problem with x idler bracket
November 20, 2008 08:21AM
I don't have a lasercut kit, so I didn't file anything winking smiley

Make sure that the rods are perfectly angled in the bushings, just like it's in the assembly instructions.
I'd say if you have the assembly mounted and hold it vertical the carriage should move downwards fast and without stuttering down but running smooth.
If that's the case you'll be fine.
If not remove one of the black bearings to find which one is causing the misbehaviour then file it's housing (be gentle)


At least that's how I would do it from here...
I'm sure Ian can tell much better what to do, so you may have to ask him if it's not working that way
Re: problem with x idler bracket
November 20, 2008 09:34AM
When I initially assembled my x carriage, some of the holes required smoothing before a rod would even go in. I smoothed it until a rod placed in the hole vertically would drop out the bottom under its own weight.

When the x-assembly is complete, it should move smoothly along - it shouldn't have to be forced. You can also use a bit of lubricant (wd40, cycle oil, or even candle wax) on the rods to help things move.

I think the reason a lot of noise is made about this is that if you finish the machine, and it's a bit tight, you have to disassemble almost the entire machine to fix it, including all the fiddly measuring of the diagionals. It's a LOT easier to get it smooth before you start.

Re: problem with x idler bracket
November 20, 2008 09:50AM
My black sleeves didn't require extra filing, only the holes they went into. One or two were a little bit loose, but once the x-assembly was complete they all seemed fine.

If your sleeves are very loose, you could use a small amount of glue to hold them to the acrylic. Or, you could wrap a small length of tape (insulation tape? sellotape?) around the bearing before you insert it to make it fit tighter.
Re: problem with x idler bracket
November 20, 2008 12:37PM
Great - I'll give that a whirl. I bought a 140mm needle file set and it is making life a LOT easier. Also purchased something called a "bastard file" which, despite its name, is fantastic winking smiley

broken bits - how to replace them?
November 21, 2008 12:46PM
I've completely cracked part 43 in half - two number 43 pieces were stuck together where the laser didn't cut all the way through and I couldn't get them apart. When I tried to file them apart they broken in two. How do we get replacements for broken parts/can someone make one for me?

Edited 1 time(s). Last edit at 11/21/2008 01:09PM by JenbotUK.
Re: broken bits - how to replace them?
November 21, 2008 03:28PM
Try emailing Ian Adkins (one of the two chaps who run BitsFromBytes) - I've found him to be very helpful. If mine was calibrated and working, I'd print you some.

For some of the parts, you may be able to form a temporary replacement out of CAPA (polymorph). Probably not for these bits, though.

You might want to try building the extruder barrel while you're waiting. My BfB extruder kit came with a small chunk of fire cement wrapped in clingfilm. I ended up leaving it for several weeks, and when I came back to it it had gone hard.
It's not a serious problem - I was able to get a big tub of fire cement from BandQ for a few quid.

Good luck

Re: problem with x idler bracket
November 21, 2008 06:22PM
you'll find some pretty strong glues for acrylic material in your hardware store,
so if you have both pieces left, you can try this first.
I glued some moulded parts with ordinary cyanoacrylic glue which went pretty well.

Since you still have both parts, you may also try to make a mould and use some resin to make a replacement.


PS Ian will surely help you, sure, but you broke the part; so try yourself first winking smiley
Re: problem with x idler bracket
November 24, 2008 02:48AM
Yes been away at a show for a few days and before that real work was getting a little mad getting ready for the said show! but back now so Jenbot please send email to BfB and I'll get replacements in the post, we don't charge for one & two off replacement bits.

Re: heater barrel tutorial
December 10, 2008 07:24AM
Hi -

Two questions:

I'm just about to go through the Heater Barrel tutorial - I noticed that 1) my kit didn't come with a copper nozel - is this something I need to buy separately or should it have come with my kit?

2) Neither side of my heater valve has an internal thread. Again, is this right or should one side have an internal thread?

Many thanks!

Re: cutting down motor shaft?
January 26, 2009 01:00PM
Hi there -

I am just about finished my XAssembly - and I am having trouble fitting my motor shaft (step 17 and 18) onto the piece marked number 50 (which is on the underside of the motor and sits on top of the clamp/bearing plates). In the instructions, it says that the motor shaft should be cut to length/filed - I was just wondering if this is actually true! Do I have to shave down the motor shaft? If so, can anyone recommend a tool to do this?

Re: cutting down motor shaft?
January 26, 2009 02:21PM
Jenn, i don't know enough about the kits to know if you need to cut the motor shaft, but if you do, this is how i did it:

short all leads together brake the motor
clamp the motor in a vice or to a table
use some locking pliers or clamp to stall the motor shaft on the opposite end you want to cut
use a hacksaw to cut it, possibly adding water or oil to cool it if it gets too hot (not sure how hot the motors can get, but i did to be safe)

I found it nigh on impossible to cut the motor without it rotating without these steps, but like this it was a bit tiring but simple.
Re: cutting down motor shaft?
January 26, 2009 03:28PM
I used a standard small hacksaw to cut the shaft to the right length. I had to cut two of the motor shafts - the X and Y motors.

I had to hold the shaft with pliers to get the cut started, but once started it cut through OK.

'measure twice, cut once'

Once you've cut the end, you'll probably need to file off any rough edges. The other thing that helps is filing a flat in the side of the motor shaft - to make it a little bit D shaped - that helps the screw hold the connector on.
sourcing filament in UK
February 11, 2009 12:02PM
Can someone tell me where to source filament in the UK? The BfB site isn't listing it anymore.
Fitting BfB pulleys
February 11, 2009 12:15PM
Also, I'm looking for any tutorials on putting the pulleys in place. I have assembled a BitsFromBytes printer. Help!

Re: sourcing filament in UK
February 11, 2009 01:37PM
There is a company here: [www.plasticweldingequipment.co.uk] but I have not used them so can't vouch for them.

I have bought some from [www.tempatron.co.uk]. I had to order it by phone and fax and so far I have not been able to use it because it is too oval to fit my extruder, about 3.6mm.

I got HDPE from here [www.workzone.co.uk] and it was fine, but not as good results as ABS. They don't seem to do round ABS.

It is so expensive over here that I have been buying it from the US from [www.plasticweldingrod.com]. The postage makes it about the same price for 10 lbs or more but they have a bigger choice of colours and plastics and the quality is good. You do have to order by phone and it does takes a while for them to make it and for it to be shipped.

I also got some from the RRRF which comes from [www.villageplastics.com]. That gave me the best results, but Zach's fixed rate shipping is excessive unless you fill the rest of the box with something heavy like stepper motors. I requested a quote from them direct but got no reply.

Edited 1 time(s). Last edit at 02/11/2009 01:42PM by nophead.

Re: problem with x idler bracket
February 12, 2009 03:49AM
We are now back on-line :-) and will have all the filaments back up either today or tomorrow including ABS. Sorry for it going off line for so long we have been updating the main website engine and porting all the data was a problem but all sorted now.

Re: problem with x idler bracket
February 12, 2009 04:24AM
Wow £46 / Kg plus £12 shipping for ABS, you have got to be kidding. If I buy 10 lbs from the states it cost $8 per lb plus $50 shipping. That is $130 for 4.5kg or £20 per Kg.

Edited 1 time(s). Last edit at 02/12/2009 07:00AM by nophead.

Re: problem with x idler bracket
February 12, 2009 07:01AM
Yes, thanks for that Forrest, I have edited the post to correct it.

Re: problem with x idler bracket
February 12, 2009 07:06AM
No problem. smileys with beer


Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison
Sorry, only registered users may post in this forum.

Click here to login