[My77gmc]

Good day all,

I have been lurking in the shadows here for months reading reviews and the questions associated with equipment purchases and I think I'm at a point that I can ask a relatively educated questions regarding what I need vs what I see...


I'm looking for something stout that can handle 4"W x 6"L x 3"H soft metal work as well as stainless steel sheet metal engraving/square hole machining max thickness .0625" with accuracy to .0001"

I have more faith in old equipment and I'm leery of anything structural made of aluminum.

I would be more than willing to mod an older machine to suit my needs, although it may be in my best interest to buy something new.

I have relatively unlimited space so perhaps a bench top model is not what I'm looking for. I also have relatively unlimited power sources from 120v 1ph, 120v 3ph 240v 1ph(or 2ph for you smarter folk) 240v 3ph as well as 480v 1ph(or 2ph) and 3ph in a large % of a megawatt. I have a 28" thick slab to put it on and a large shop with a spot the size of a small car to put it.

My only limiting factors are cost and what I can get into the elevator which is limited to about 4'W x 6'L x 7'H and 2500#

As for cost I would really like to get set up with a machine, software and basic tooling for under $5k, which I think may be unreasonable.

That said my employer is interested in enabling me to repair his 100yr old mechanical equipment and I would bet he would double my money, or more, if it was worth it...he has an uncanny ability to judge things to his benefit without any understanding of what it is, like some sort of 6th sense...huge benefit to me I think he has a highly vocal guardian angel....


I have been looking at the Tormach PCNC770 - seems to fit the bill but is a little bit more than my original personal investment limit

In the future I will need to duplicate copper alloy bearing races that are approx 6" OD and 4" high, that are a part of a 1935 150 ton chiller "rebuild to original specs" project, several years down the road. I think that's the largest thing I see in my future


So then to my questions...

Are the any quality old machines that are commonly upgraded with CNC gear?

Is the tormach machine a fit for my needs from an experienced user standpoint?

Are there high quality small 3ph machines? Only reason I think this is important is my old friend machinist Jerry 'Barney' Barnette always told me if I'm ever buying my own equipment to not waste my time on single phase unless I didn't want "real power" at my fingertips...but then his milling machines were all medium sized floor mounted milling machines like a 24"x48" bed for example.

Lastly, is my assumption that aluminum bracketry and structural components should not be considered, valid for what I'm looking to accomplish?


Thanks in advance!
Jim

[Tkamsker]

Hi i think what you Need is Not so complicated to achieve i was in similar Situation and made an Excel comparison List because you will See there is a Lot of options.
First if you live in us buy us stuff if in Europe Europe stuff all of that cheap i think doesnt Pay off.
Probably in your Case an Good machine to retrofit will be best Solution
I right now retrofit a bridgeport 412 if you get One cheap might be an Idea for you. The New machines like tormach or the canadian might me also ok but See what you can get used close to you for retrofit and See if Budget allows it ,..


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[awerby]

If a Tormach is too expensive, you're going to have to look pretty hard for a machine that will hold .0001" tolerances on a sizable part. While machines like that certainly exist, they are in a whole different price range from the sort of machine you can buy for $5k, unless you're very lucky. One of the precision-ground interior-cooled ballscrews that runs it would likely cost that much. I'd say either relax your tolerances (+/-.001" is much easier to achieve) or get a lot richer...

Andrew Werby
www.computersculpture.com

[My77gmc]

Thanks for the help!

I am generally an unreasonable perfectionist...

Through suggestion of others I think I may go this route...any thoughts?


Purchase a seig m6c6 combo and mod it with aftermarket CNC kit, basically using the iron parts... Would cost about $3800 plus shipping and a fair amount of time.

The accuracy is because I want to make stainless steel punch cards for a music box and the timing is pretty important. Very small slots/square holes in 1/16" ss sheet a bit smaller than a 3x5 flash card. Holes are about .0625" wide and vary in length from .0625 - .125 or so. Original machine used cardboard punch cards, this one has a deeper bed and more stout mechanism basically. All the rest of the parts are hand cut and filed or robbed from used copier machine mechanisms. I was told this would need a router but could be done with a mill...

Thanks again:drowning:

[Tkamsker]

Hi i know if you mill Steel you Need a Real mill no Router it has to be rigid i have a mill like tormach 1100 just better (European Build no China stuff ) and i Tried to Mill blades for an chrasher where i have to use 3mm Miller my learning is Even if your machine is Perfect accurate in some Situation the Miller bends you then have to See how to avoid or minimize that ,. Probably your Solution might be vmc Mill and 4 th axis ,.. Then the Software is important ,..


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[My77gmc]

Ok thanks, it was suggested that the punchcard process be rethought, and I'm going a different route on that...

[Tkamsker]

Probably i was too short i meant that for good result the Software costs will be significant ..

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[awerby]

To make square holes in stainless sheet, milling is not the method I'd advise. Thin sheet is hard to hold onto effectively; it tends to pull up while being cut. And your corners will never be very square, since you're cutting them with a round cutter. I'd suggest making a die (or a series of dies) to punch those holes instead.

As for your choice of mill, you seem to veer between the extremely precise but unaffordable and the affordable but crappy. None of those cheap Asian mills will come anywhere near your stated tolerances, and to do that they'd need a lot of work. Often, they aren't even square, as shipped. And the cheap CNC retrofit kit with rolled ballscrews is not going to add accuracy; those C7 screws are typically off by multiple thousandths of an inch per 300mm section, which adds up. Here's an old article in the Zone which talks about this in layman's language: http://www.cnczone.com/forums/linear...ew_basics.html Here's a more general article on rolled vs ground ballscrews: How Rolled and Ground Ball Screws Stack Up | Archive content from Machine Design

Andrew Werby
www.computersculpture.com