Printrbot Hobbed Bolt Dimensions

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Printrbot Hobbed Bolt Dimensions

Postby Tdeagan » 2013-Jun-Sun-14-Jun

I'm building out a second extruder and beginning my quest for another hobbed bolt. Alas, Printrbot is out of stock. As I began shopping, I realized that these bolts vary in significant ways and I couldn't find a reference for the stock bolt from Printrbot. This post is an attempt to document the dimensions of the stock Printrbot Wade's Extruder Hobbed Bolt and ideally generate a conversation that will help determine a good second source to acquire them from.

While the majority of hobbed bolts on the market are M8 X 60mm the stock bolt from Printrbot is a 5/16" x 2" 18TPI with a 1" shank length and 1" thread length. This is a very close match to a standard M8 x 1.25 50mm bolt. They are not identical, but they are extremely close and should be within tolerances for hobbed bolt use. Nearly every vendor I have found online sells M8 hobbed bolts, though 5/16" are out there.

It's also worth noting that hobbed bolts sold for Greg's extruders may not work for Wade's extruders. The Ultimaker site lists an M8x60mm hobbed bolt but warns:
Please note this bolt's teeth are directional. The Greg's Extruder design is the reverse of the Wade Extruder Design. This bolt is not compatible with a Wade Extruder. It is compatible with a Greg Extruder.


The critical dimension is the distance from the bottom of the bolt head to the center of the hobbing. Hobbed bolts found online come in many variations on this dimension, 29mm seems common. Many vendors allow you to request different distances. Many don't list this critical dimension at all!

The Printrbot bolt is hobbed at 21mm:
hobbed bolt.jpg

I suspect this is an artifact of using a 2" bolt, you really couldn't manage to move it much farther or you'd be hobbing in the threads. On My V1 PB+, I find that I'd really like the hobbing to be slightly farther out, it's not quite centered even though the bolt as tight as I can reasonably make it. (That's probably why so many of the bolts online are 60mm instead of 50mm.)

Has anybody had a satisfactory online purchase of a replacement hobbed bolt?
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Tim Deagan
KC5QFG
(optional Dual Extrusion) Printrbot Plus V1 [3/2013]
bed stabilizers, bed levelers, Y & X belt tensioners,
50mm fan mount, LED ring light, Z-axis screw Isolators,
Z-shaft stabilizers,optional Bowden conversion, GT2 belts/pulleys,
M8x1.25 Z Screws, Flex. Z-couplers,
RAMPS 1.4 w/ LCD,
Quick Change Extruders:
Option 1- Dual hybrid geared Wade's/Bowden w/ 3mm & 1.75mm Ubis,
Option 2 - Dual direct geared Wade's w/ 3mm & 1.75mm Ubis
Option 3 - Single geared Wade's w/ 3mm or 1.75mm Ubis
Option 4 - Single belt drive Wade's w/ E3D
MIC-6 metal bed
Thingiverse Profile: http://www.thingiverse.com/tdeagan/designs
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Tdeagan
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Printrbot Hobbed Bolt Dimensions

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Re: Printrbot Hobbed Bolt Dimensions

Postby brookdrumm » 2013-Jun-Sun-14-Jun

I'll get some in the store this week. They are a major pain to make and we reject any with any defects... It's hard in our machinist ;)
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brookdrumm
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Re: Printrbot Hobbed Bolt Dimensions

Postby Tdeagan » 2013-Jun-Sun-17-Jun

Sweet! That means I can order my bolt, Kysan and Ubis all at once (I'm a shipping miser.)

Last night I printed the ExtrudrPlate - Printrbot Extruder Tray ( v1.7 ) from sponnet and it assembled nicely. I tried it with the hobbed bolt from my stock wooden Wade's Extruder and it worked great.
  • 0

Tim Deagan
KC5QFG
(optional Dual Extrusion) Printrbot Plus V1 [3/2013]
bed stabilizers, bed levelers, Y & X belt tensioners,
50mm fan mount, LED ring light, Z-axis screw Isolators,
Z-shaft stabilizers,optional Bowden conversion, GT2 belts/pulleys,
M8x1.25 Z Screws, Flex. Z-couplers,
RAMPS 1.4 w/ LCD,
Quick Change Extruders:
Option 1- Dual hybrid geared Wade's/Bowden w/ 3mm & 1.75mm Ubis,
Option 2 - Dual direct geared Wade's w/ 3mm & 1.75mm Ubis
Option 3 - Single geared Wade's w/ 3mm or 1.75mm Ubis
Option 4 - Single belt drive Wade's w/ E3D
MIC-6 metal bed
Thingiverse Profile: http://www.thingiverse.com/tdeagan/designs
User avatar
Tdeagan
Waiting for printbed temp...
 
Posts: 149
Joined: 2013-Feb-Fri-14-Feb
Location: Austin, TX
Reputation: 11


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