blackToe vs Pilot Pro

[kousha]

Hi there,

First of all, sorry if this is a wrong board to post this, I have absolutely no idea where to post this question!

I need to build a CNC machine for a small company. They only requirement they have given me is that they want a resolution of about 40microns.

I have been reading online, and I really like the blackToe cnc. But its made out of wood!! It makes me feel weird to want to build a cnc (that would be cutting plastic and aluminum btw) out of wood!

I am from Vancouver, so it is pretty humid here. Should I go with the blackToe (and wouldn't the wood break down overtime?) or with another one such as Pilot Pro?

[michaelthomas]

I built a Blacktoe replica a while ago, although mine was more robust in many ways.

I can tell you that it will not cut aluminum to .020 of an inch.......let alone 2 tenths. You would have to take a million passes anyway. IIts best to just say it won't cut aluminum.

It is only suitable for very light work......if you are expecting to hold .020 inch. Those who might extol its virtues would be using a tape measure to determine accuracy....not a micrometer.

Regardless of what may be said......the chain drive is not 0 backlash, either. If you mounted an indicator against the spindle.......you could deviate it by .125 inch with one finger.

Its a good machine for balsa or other light materials that don't have to be real accurate. I built mine to cut model airplane kits, and it did an acceptable job for that.

I believe you have unreasonable expectations for even mills that cost hundreds of thousands of dollars. .0002 inch is awful small.

[ger21]

.0002 inch is awful small.

40 mirons is .0015, according to an online converter I used.

The Pilot Pro is probably 10 times better than the Blacktoe. And still probably not rigid enough to do what you want. I've seen many posts about machines using much larger extrusions than the pilot pro, and still not having enough rigidity for cutting wood at higher speeds.

A machine for cutting aluminum needs to be extremely rigid is you want to be able to make your parts in a reasonably amount of time.

Do you want your parts accurate to within 40 microns? Because that's not the same as having a resolution of 40 microns.

[michaelthomas]

Oops......I had 50 microns in my head.......but I still put one too many zeroes into my calculator.

Unfortunately, it still doesn't change much with concerns about the Blacktoe being up to the task.

I cut the aluminum brackets for my mill on the cnc router at my former workplace. It's an Onsrud Panel Pro with a 20 HP spindle. I think they paid around $200,000.00 for it new. It wont hold .002 inch on 1/2" 6061, either. That's with a 1/2" 3 flute taking 1/4" DOC and a 010" finish pass .......which would still be considered mild by most VMC operators.

I have done bearing pockets on it by interpolating the bore with an endmill, and was able to get a reasonable press fit (after sneaking up on the finish)......but the hole was not nearly as concentric as a boring head. It was more of a press fit at certain points instead of all around.

You need a VMC , not a router, for what you are asking.......even for .0015". Thats a lot more reasonable than .0002", though.

I assumed that accuracy was meant by resolution.

[txcncman]

I have a hard time imagining a "home built" machine that would be both cost effective and accurate and profitable, versus a "good" used commercially built machine.

[flux_001]

Hello-

I built the 2x4 blacktoe about two years ago. It has been a nice DIY machine to have at home to figure out machining wood(cedar,plywood), foam insulation and renshape, hdpe etc.

Last week I experimented with some feeds and speeds- I milled some 6061 and 6062 1/4" aluminum plate. I was really careful on ramping in to a (rediculous) doc of .02" and slowly moved through the plate at various depths I use SGS radius carbide endmills. I dropped the router down to a low rpm and gave it a whirl with a little oil. If you work at the offsets in theory you could come pretty close to holding some kind of dimension but It would take a ton of work and time and for a one off small part it works for me at home. The issue I have is squaring and gauging parallel because everyonce in awhile the x axis motor rod clamp slips and can go out of square. I need to drill and grind a flat in the rod and use an additional set screw or something.

Regarding water / moisture I polyurethaned the parts with multiple coats before assembly. The nice thing is you can mill any replacement part or at least repair it fairly inexpensively since you put it together yourself. A real production shop is a little odd to use this but in my trade/discipline +/- 1/64" is exceptional And this machine can achieve it in most of my applications using my CADCAM software.

Good luck this may not be the machine for you though

flux