DIY mill...

[irving2008]

eBay got to me again.... picked up a brand new Dewalt D28885 500W 1.7kg die grinder as the basis for my milling spindle for £40, bit cheaper than the £100 asking price for a 500W Kress. There are a couple of places on the Net doing spares for the Dewalt and they list the spindle bearings as type/size 608VV so should be possible to upgrade them later if need be...

Still havent decided if this is going to be a fixed or moving gantry machine... I'm tending towards fixed gantry, moving table in X, moving spindle in Y & Z

[wiremonkey]

Ha! Words of wisdom amen23! I built an aluminum extrusion machine and it works really well on plywood and acrylic and could certainly do some engraving, but I've started down the path to milling 6061 aluminum and I can do it, but not well. So, I thought, heck I'll just do some stiffening here and there and... flush... $$$... swirl... Anyway, I'm contemplating how to upgrade or keep this machine for wood and build another much smaller X/Y table type out of steel for milling. I can't really decide the way to go and my budget is very limited. Or maybe I sacrifice cutting area and use the parts from the existing machine to make the mill. Hmmmmfffff! Anyway, I'd love some input from y'all who have been down this path. I love CNC and making stuff, but I'm growing a bit weary of making stuff for my CNC.
If any of you would care to see my video saga on youtube, please take a peek and offer all the jabs and sneers you can muster. I can take it!
https://youtu.be/2QTZa2Ge9A0
Cheers!

[irving2008]

Yes, I did some more research... although I havent broken my airdrill out of its packaging the big issue with airpower is lack of torque and constancy of speed... so I'll go back to electric motor....

I noticed on eBay a few drill motors, 14.4 and 18v replacements for cordless.. The specs on these look promising 100W, 55Nm torque at 10mm (I need ~50W, ~15Nm) but the spindle speed will be low, maybe 1800rpm, although I read that 14v motor PWM'd at 25v will run faster... maybe I could belt drive it, 2:1 ratio will give 3600 rpm @ 25Nm...

I also came up with a plan to fix mount the motor and belt drive the spindle on a sprung idler so the spindle could traverse the Y plane but the motor remain stationary. Of course the Z motion will require a splined drive shaft so the upper drive pulley remains fixed.... I'm sure there's a catch somewhere, just don't see it yet....

[Robin Hewitt]

I was feeling grouchy one day, reckoned my mill was overpowered at 2hp, noisy, had a poor selection of speeds and was not very quick... so I bought a pukka 1hp motor with a matching digital phase converter and computer cable.

Slow to twice normal speed with no loss of power, soft starting, reverse, da woiks.

It's been lying around ever since, but I will do it one day... honest I will

[irving2008]

I was feeling grouchy one day, reckoned my mill was overpowered at 2hp, noisy, had a poor selection of speeds and was not very quick... so I bought a pukka 1hp motor with a matching digital phase converter and computer cable.

Slow to twice normal speed with no loss of power, soft starting, reverse, da woiks.

It's been lying around ever since, but I will do it one day... honest I will

and your point Robin? I always finish what I start, well mostly

[Robin Hewitt]

My point?

My point being that I believe the best way to drive a mill is a DPC but I have yet to explore the possibilities.

I have a feeling it would be nice if the machine could autoselect the correct speed from the G code, not start with a bang, maybe apply the brakes so I don't have to wait while it slows down etc :D

[irving2008]

Well the design progresses slowly...

Been thinking about ways to mount my leadscrews and looking at bearings for the same, namely the 608ZZ that Lee sells...

I have some questions...

1/ Do I really need bearings for 10mm leadscrews max length 400mm. I've not done the calcs yet but gut feel says yes even if its just for the far end....

2/ whats the diameter of the inner rotating part of the race (not the shaft diameter)? My thought is to use a similarly sized OD/8mm ID washer that would act on that to preload the leadscrew with an 8mm ID thrust collar. How do others suggest preloading the screw or do you rely on the motor to control horizontal movement of the screw?

3/ Was thinking about boring out an SK12 or SK13 round rail mount to fit the OD of these races, since that would put the screw centreline at the same height as the rail centre line and is easier than constructing somehting from scratch IMHO. Do you see any issues in doing so? Else what do people suggest as a way to mount the races?

I'll have to machine the ends of the leadscrew down to 8mm (they are 10mm x 2). The leadscrew i have is 400mm long which with machining allowances will work with a 230mm table on 500mm rails giving of 460mm of travel (20mm anti-crash space!).

Not having seen how others do this close up, this is my best guess as to how to approach it. Thoughts?

[Lee Roberts]

lol, OI YOU LEAVE MDF ALONE !!!

Yes it is Delrin.

Yea i used delrin as a drive nut under the table as well mate.











Just let me know when you need anything ill quote you happy !

Lee

[Lee Roberts]

Forogt to say, i also sell ACME Delrin Drive nuts as well.

They work jsut as well for ACME, i think you may have got ballscrew from Dice.

or was it Anti-Backlash x3pcs 10x2 Trapezoidal + Delrin Nuts CNC ?

[Lee Roberts]

Ahh yes there it is: View Item