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25-09-2017 #1
Lovely work once again well done.
I would say release updates when you are ready and at a rate that feels enjoyable. It's easy to think everyone is tapping their fingers wait for new information but you are doing this for free and for fun so don't feel pressurised.
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25-09-2017 #2
Awesome work.
Some questions.
What 3D printer / material are you using?
In terms of your bed, you always seem to have screws for workholding in the correct places. Are you drilling the holes (or milling them) and then drilling / tapping into whatever material your bed is made from on your mill? I struggle with workholding at time yet you make it look easy.
Thanks
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25-09-2017 #3
I'm using my trusty old makergear m2... I've had it for about 5 years now and it's still churning out lovely prints. I actually designed myself a new super duper printer which I'll make one day once this CNC machine is done, but that's really just because I want a bigger beast with quad extrusion and dual independent heads. Oddly enough makergear just announced their new version that does have dual independent print heads, but I would still want the larger build platform to make best use of them (I love the idea that you can print two sets of the same items simultaneously, effectively doubling output of parts if you need more than one of anything).
Material is some stuff called Cheetah by ninjatek. It's a flexible rubbery material a bit like hard skateboard wheels, 95A on the durometer scale... fairly easy to print with if you have a direct extrusion head. I believe it even works with some bowden printers.
Workholding wise for these big pieces I have been using a 12mm sacrificial sheet of SRBP, skim it level and then where the parts have suitable holes I run a "jig drill" drill cycle through into the bed that then allows the hole to be tapped and a screw inserted without moving the part. For the exterior clamps I either try to find a previous hole that works or just drill a new hole and tap. I keep going until either I skim down too far or it becomes like swiss cheese and then I replace with another sheet.
It's not the cheapest option I'm sure (a sheet that size costs around 30 quid) but it's a wonderful material for stability, machinability, coolant resistance and accepting threads/dowels etc.
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The Following 3 Users Say Thank You to Zeeflyboy For This Useful Post:
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25-09-2017 #4
Thanks for that. Can you explain a bit more about how you might do the drilling / tapping into the SRBP in one step without moving the part?
Thanks
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25-09-2017 #5
Yes absolutely, make sure if the bolts are sitting proud of the surface you set an appropriate retract height. I actually always just set it at 25mm as a matter of habit, it doesn’t waste much time at all as all moves back down to the top height are done at rapid’s speeds.
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26-09-2017 #6
I just got a piece of SRBP to try. It's incredible that it's made out of resin and paper, it looks really tough and quite heavy. I only got a 400x300 piece, in 15mm, as it's quite expensive, I think you use larger sheets?. I am guessing that Tufnol is a brand name, but the same thing?
I just wanted to ask roughly how thin does it get before you discard it, with regards to having enough thread left in the holes with sufficient strength to clamp the piece, 8mm or so? If you use M5 bolts, I suppose you need a good 5mm of thread? Secondly, I assume that you don't skim it every time you cut a new piece, provided you have enough of a flat, clean area left for the next piece to sit flat, is that right? Also, what's your favourite tool for skimming the SRBP? Does it machine similarly to Delrin? (the only plastic I have machined).
Keep on posting about your progress, the more the merrier:)
Edward
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26-09-2017 #7
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26-09-2017 #8
I paid £44.32 including the £15 for UPS, for the 400x300 piece. I guess if you ordered a few pieces it would just be the one-off transport fee. At least they provided an invoice, so I can discount it off my tax as a legit expense.
They also call it Phenolic Sheet.
Edward
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26-09-2017 #9
At prices of Tufnol I'd glue it to a 12mm sheet of mdf then you can mill through the whole lot screw wasting any.
If you have issues with losing 12mm of travel on the Z then you really have issues lolLast edited by Desertboy; 26-09-2017 at 03:45 PM.
http://www.mycncuk.com/threads/10880...60cm-work-area My first CNC build WIP 120cm*80cm
If you didn't buy it from China the company you bought it from did ;)
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26-09-2017 #10
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