Wade extruder slip - no grip

Dear all,

I'm struggling for a few weeks now with my Wade's extruder. It does not seem to extrude nearly enough plastic to print. At times, when testing it not printing, and when the stars were aligned (ie I can't really tell the difference in settings) it was extruding at a decent rate, but not for a long time. The key issue seems to be the grip of the hobbed M8 bolt. The "teeth" seem small, although it is difficult to compare with the wiki pictures accurately. It clogs with PLA quickly and doesn't push the filament down

Here are a few questions/hypotheses
- How do I know how deep the hobbing needs to be ?
- I didn't pre-file the shoulder of the bolt. I do have a slot that looks reasonably deep, somewhat similar to Wade's picture on the wiki, but is it the cause of the problem ?
- I don't use springs but just tighenning the nuts. I read multiple people had success with this setting so it seemed alright. But how strong should they be tightened ? Can it be too tight ?
- I am printing PLA. I run at 190°C (well calibrated thermistor). I an it at 210°C and the lower melt viscosity helped extruding more. Is it a long-term solution or can it damage the PLA ?
- I would like to try the alternative solution of cutting the bolt thread perpendiculary with a Dremel, as described on the wiki. Anyone tried that ? How "foolproof" is it - cause I'm a real fool :-) ?

Thanks !

That wiki page is starting to 'rot'; there are a lot of edits on there that I don't agree with, but haven't had the time to fix all of them.

The extruder won't work as intended without springs. They have to be pretty strong springs as well; specs are on the wiki page still. The dremel cut slots are a bad idea as well, if you want even flow rates.

You should never have to clean the teeth of the hobbed bolt - any buildup there is a symptom of not enough tension on the idler block, probably related to the missing springs, or a jammed hot end.

Post a macro shot of your hobbed bolt and I can tell you if it will work. I usually aim for a finished diameter of less 6 mm on the hobbed section.

Wade

@Wade

I have not found springs in the UK strong enough to work.

So I just gently tighten the 4 screws to get a good grip for extruding. It seems to work ok.. so far..

I have several boxes of hobbyist springs selections sold in the UK none of them have enough spring in them.

I have tried the springs from various plastic clothes pegs they have the strenth but not the length or the internal diameter for 4mm screws. Note:- the clothes pegs/pins that have a "compresion spring" not the more common "twist spring" type.

Cant find a picture other than the traditional twist spring type.

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Bodge It [reprap.org]
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My rep strap: [repstrapbertha.blogspot.com]

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Here are pictures of my bolt - what's your opinion?

The teeth look way to small to me.
Try using an M4 tap instead of M3.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

The teeth seem to disappear in the bottom of the groove. It should look more like this: [2.bp.blogspot.com]

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[www.hydraraptor.blogspot.com]

that's quite a difference

How about running a short piece of filament through without any nozzle/heater? That usually shows how well the teeth are biting and what the compression of the filament is. I squash it more than most (probably to 66% of OD for abs) but I can extrude at least as fast as anybody else, with good results.

I had lots of issues trying to use an extruded without springs. if you can't get springs of sufficient strength, how about cutting some rubber washers from an old inner tube (or some other source).

Hi Andrew - good point but I already glued the hot end

Hi Greg - thanks for the advice I can try that

If you don't use springs with Wade's extruder (I don't) , be sure that you don't tighten the screws so much that you deform the filament. It should be just tight enough to grip, but you should be able to push and pull on the fillament without too much resistance (letting the bolt turn, of course).

The springs help if the diameter of your filament varies much. In my case, the filament seems consistent, so I don;t see problems much.

Personally, I use a hack saw blade to cut a 0.5mm ditch into the bolt, and then use the 3mm tap to hob it.

I looked at the hobbed bolts being sold by various people noticed that they all use a much bigger thread so I used a much larger thread at random from my taps box its 7mm - 8 mm tap this is suficent for both 3mm and 1.7mm filament.
I also could not find Springs strong enough and just tighten the four clamp screws down 1/4 of a turn until the grip is just making very slight marks in the filament.
You know its too tight if you need to apply lots of force to the fillament in to start it going. A gentle push and turn of the large gear and the clamp is tight enough.. not very sientific but seems to be a good method of setting the clamp screw tension.

It also means it not a mamoth fiddly task to change the fillament colour.

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Bodge It [reprap.org]
=======================================

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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

Hey Bodge!

I just want to say... you CAN get the springs in the UK! If you follow back on the wiki page there are recommendations to the spring supplier "Springmasters" (http://www.springmasters.com/) they are UK based, there is no web ordering system last time I checked and you do have to order over £15 worth of springs for them to deliver. (wiki link [reprap.org] near the bottom of the wiki)

But you can pick up springs for the print bed as well (if you want / need) or buy a few more sets of the extruder compression springs and sell them on here / emakershop / ebay to other reprappers!

I bought the same springs as Adrian for the extruder idler ( D12100) unfortunately I cannot remember the springs I bought for the Print bed, but I can dig them out if need be.


And on another note, I am having the same issue with the hobbed bolt... I think I am going to remake mine with an M4 tap... and go for reproducing it like Nopheads (mines deep but not quite THAT deep lol)

Cheers,

IainA

I used a 1/4" tap to hob my bolt. That's approximately 6mm, but I think the thread is steeper, so the cuts are a little deeper than M6 would be. It transports extremely well, even without springs.
I never had it slipping once, but when the tip got cold, it once pushed the hot end off the extruder body- still no slippage. I can't even hold the filament with my hand when the extruder is transporting.
So my recommendation: go with a larger thread size for hobbing the bolt. M5,6,7 or some imperial equivalent should all work.

ST

I have used same design and have same problem with M4 hobbed bolt. So i changed M4 to M10 and it helped.