Hallo
Have some of you replaced the Hobbed Bolt of the K8200.
Im looking for a better one but cant find a shop to get one that would fit the K8200.
Maybe you can give me a link to a shop ?
bg
I just ordered this like 5 minutes ago:
ebay.nl/itm/Hobbed-Bolt-M8-f … OC:BE:3160
Im not even quite sure yet if it will fit, but I think it will :).
Hi,
i have made one myself with this tool from thingiverse.
There is a tutorial video too so it is quite simple to build one by yourself.
These are mine images of the process using a stainless steel bolt (bought in a do-it-yourself store for few bucks)
note: you have to put at first some washers on it because the hobbing position don’t fit for the K8200 extruder!
And i’m really satisfied with the result.
Don
Hi,
[quote=“P4man”]http://www.ebay.nl/itm/Hobbed-Bolt-M8-for-3D-printing-Prusa-Mendel-RepRap-Hardend-steel-/301001808701?ssPageName=ADME:L:OC:BE:3160
Im not even quite sure yet if it will fit, but I think it will :).[/quote]
it should. You’ll probably use two locknuts, one on the backside and another one “inside” the large gear. Alternatively, a normal nut can be used for the gear in combination with loctite or a similar adhesive. Either way, the axial position of the gear can be chosen with several mm tolerance, which should give enough space to accomodate the given dimensions of the extruder.
Cheers,
kuraasu
Thx for the quick answers !
I ordered this onei hope it will fit …
reprapteile.de/mechanisch/extrud … -bold.html
I hope that this will fix the Problem with the very badly extrusion , i use to print small objects and its allmost imbossible to calibrate the correct ExtrutionWidth.
Looks identical to the one I just received. It does fit, but only barely. I had to reverse the locknut on the gear to make sure it actually locks, thats how tight it is. But it grips fantastically, it has no problems pushing my nylon now, even with the spring barely touching the bearing holder.
Hi P4man,
if you can have a look at it some time, could you check whether the dimensions mentioned on ebay fit? Especially the 2.5 cm from filament center to the end and the 6 cm total length?
Cheers
kuraasu
Sorry, I missed this post. Ill do the measurement if I take it apart next time.
One small note, you will have to re calibrate. Should be obvious, but I sort of forgot to do this :p. When I extruded 100mm I was suprised to measure only 84mm coming out. I should not have been surprised of course, given the smaller diameter of the gripping part of this bolt. But the reason I was surprised was that I was getting quite decent prints using an extruder multiplier of “only” 107.
As for fixing my issues with printing nylon; it did and did not. This bolt has no problem whatsoever gripping the nylon, but instead of slipping, it will simply cut a hole in it. That is even with with the extruder spring at minimum (and barely any) pressure. At some point during the print, it just stops extruding and the hobbed bolt will slowly cut the nylon filament in half.
I tried everything I could think off, slow print down dramatically, vary temperature between 220 and 260 to no avail. Its a shame, because the parts that do get printed look great and are unbelievably strong and with an awesome surface texture. But Im giving up on Nylon for now.
Hi guys,
I ordered sort of this: ebay.co.uk/itm/310852370924? … 1439.l2649
I say ‘sort of’ cos although I paid that price, that one is not for a velleman and I actually sent him measurements for our printer and he made me a part with all the correct gaps - it is literally perfect and cannot advocate enough the purchasing experience. If you tell him it is for a Velleman k8200 he now not only knows the dimensions but will probably have some from the run he did for me and so just send one on and they are very cheap.
I put it in last night and have quantitatively measured how much better it is than the original - I can now set the flow ratio down from 1.35 (old very slippy original part) to 1.01 (new bespoke grippy part) to achieve the same result. As a result of the better grip I can do faster+longer retractions and hence get hairless parts even when deliberately over-flowing in order to get super solid strong parts for mechanical builds
Further details on statement above:
As you all know you should calibrate to get just the right flow ratio for your particular build and for the temp and the filament used etc. I have got it down to just one cube print - caliper measurement - one more print - final flow tweak (used to take me 3 permustations at least to get right).
For the reel I have going at the moment I WAS using 1.35 in Slic3r to get a calibration cube to just the right dimensions - very good surface quality and no hairy rubbish which can result from failing retractions on non print moves when you have too higher print head presure. WITH THE NEW HOBBED BOLT: same reel, same day, 1.01!!! I know that sounds extraordinary, but the new one is gripping it so well I am genuinely using that tiny value to extrude the same amount - goes to show how much the other was slipping!! Also, I tried just for fun, turning it up again, which I do for mechanical parts where I don’t care about surface so much, but want a very solid part for strength to see how the retractions fare - with the original hobbed bolt I couldn’t turn it to highter than 5mm at 65mm/s without it just slipping and not making any diff. Last night, with a high flow ratio so high plastic pressure in head (with new bolt and this particular filament my ‘correct’ flow was as above -1.01- so I turned up to 1.06) I turned the retractions up to 8mm and 100mm/s to see if I could eliminate hairy retraction failure (correct term ‘ooze’?) and it worked! Is I say, with the old bolt I wouldn’t have been able to retract that fast or far without it slipping and not really retracting any further than the 4mm@65 that I normally use.
Anyway, am very chuffed with new bolt so wanted to pass on experience.
Thanks,
Danny