Need help with Medel extruder drive (Where to buy bolt?)

Hey all,

I have an older Mendel ( [reprappro.com] ) that looks kind of like this:



Though I use only 1 filament, not 3

My extruder drive looks like this: [reprappro.com]



The center shaft of the part (shown below) is a M3 x 25 mm (I think) bolt, with a hex head.



That screw part that extends above (in the photo) the hobbed part fits into a bearing to keep the shaft stabilized while turning. My printer is quite old (at least 4-5 years now), and that screw part has gotten worn. This allows the tip to wobble during rotation, which has allowed the filament to slip. So my prints will have areas of under-extrusion, depending on the position of that gear drive.

So I want to replace that bolt. But for the life of me, I can't find a seller on the internet. All the M3 bolts I can find are "cap head", meaning round. That won't work, because the bolt has to have a hex head to help transfer the torque from the gear into rotation of the bolt. See photo below



It seems that I have previously found a RepRap store where parts for the printer were sold, but now I can't find that either.

Can anyone help me with a link to where I could purchase a replacement bolt?

I have thought about getting a more modern extruder drive, but I worry that it would have a different extrusion rate that would have to be accounted for in the Melzi controller board. And I don't know how to calibrate that. So I have just decided to stay with the same for now.

Thanks so much in advance.

Kevin

Also, any other suggestions also appreciated.

Kevin

Update: I have found some at Fastenal

[www.fastenal.com]~

Still deciding if these will work...

I guess I am answering my own question, but I have decided to purchase some from Fastenal. I'll post back if they don't work.

Kevin

Searching ebay UK for "m3 hexagon head" brought up a number of suppliers. RepRapLtd sells many of the parts for printers previously sold by RepRapPro, including m3 hex head bolts.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thank you for your reply. I just tried there, and most of the "hex" that I see is a counter-sunk head such that it can be screwed in with an Allen wrench (That is what we call a hex driver in the US, I'm not sure if that is a universal name or not). There were a few with a true hex head however, such as here: [www.amazon.co.uk]

I think I was searching US Amazon before, which doesn't seem to favor metric fasteners.

Thanks again!

Kevin

Yes, "m3 hex" returns socket cap screws, but on eBay UK "m3 hexagon" returns hexagonal head screws too.

Edited 1 time(s). Last edit at 12/30/2017 03:39PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi,

Thanks for the mention David. RepRap Ltd do indeed have spare parts and components used in the RepRapPro kits - Fisher, Ormerod, Mendel and Huxleys.

Kevin- If the parts you have ordered for your Mendel don't work out, let me know and we can arrange replacements. The fasteners we supply can be purchased individually so no need to buy 100s of one bolt if you only need one or two.

Best wishes
Sally

Sally Bowyer
RepRap Ltd

Sally,

I ordered some bolts and they came in the mail yesterday. I haven't had a chance to work on this yet. I appreciate your offer to get me going.

For my future reference, is this done on an individual basis? Or do you have a web store front? If so, could you post the URL?

Thanks again.

Kevin T

Hi Kevin,

We do, see here.

And specifically for the M3x25mm Hex head screw see here

Best wishes
Sally

Sally Bowyer
RepRap Ltd

Sally,

That is what I was looking for. I will use that resource next time.

Thanks
Kevin T