[cndingus]

Hi, long ago I purchased a Chinese 6040 and... it's not what I need. I make one-off small parts typically out of aluminum that need a solid tolerance (usually under 0.004 arbitrarily). After pulling my hair out trying to get that machine squared up, I'm giving up and moving on. There's more to life than that!

I am considering the PCNC440 or the PM728VT with PM's in-house ball screw conversion kit.

As a new machinist I really need help figuring out which one to buy. They are in a very similar price range once fully equipped. I'll try to list my perceived pros/cons:

PCNC440:
Good:
Works out of the box
Great support
Accurate
10k spindle chews up aluminum
Power drawbar ready (for down the road upgrades)

Bad:
Small work envelope
Y axis might actually be too limited?
Casting twist out of the box means the machine must be shimmed by end user
Tramming not as easy as 728
0.75 HP spindle
Shipping is like $500 more than PM??
Open loop
1-2 year? warranty

PM728VT
Good:
Great work envelope
Large y travel (8-10")
1 HP spindle
Accurate from what I can tell
Made in Taiwan
Can use a closed-loop motion control kit
5 year warranty (includes CNC parts if you use their hardware kit)

Bad:
Requires a retrofit which always introduces variables and complexity
Low spindle RPM -- not so good for aluminum?
Power drawbar capable but unsure of reliability of company that makes them (Priest)

I think the common denominator here is the following points:
Spindle speed
Warranty
Y axis limitations

Does anyone have advice for me? I cannot afford the 770 otherwise I'd be all over it. I also do not want a heavy machine as it needs to fit on my workbench (I have a small garage; I will make a strong workbench to support it).

It seems like a better idea to go with the 278 but I've never converted a CNC before, it's all pretty new to me, and although I'm tech savvy (software engineer, mechanically inclined), I don't want to take on a project that's going to end up being a headache like my Chinese 6040. However, it does seem like the better value.

Thanks in advance!

[metalmayhem]

Pcnc440 twist out of the box , I've never heard of that ? . I pulled my machines out of the crates , dropped them on bases and ran from there . I'd more expect twist out of the other mill .
Tram isn't an issue on the 440 , any time I found tilt in the head it was because the gib needed adjustment . Thats only happened a couple of times over the years .
open loop steppers run perfectly fine and closed loop isn't going to get you any further ahead or closer to servo run .

You can squeeze a bit more out of the y than what it is set to , and the x can be pushed to 12" by replacing the ballscrew with a longer one .

Don't be fooled by the .25hp difference in the motors because they are completely different setups . Those companies claim big tools but the reality is they can't handle them

I ran retrofit mills for a few years before buying my 440's and I'll never retrofit a mill again . My g0704 is laying in pieces on the floor and I highly doubt it won't go to the scrap yard in the next yr or so and the others are rusting in my garage . The problem with most of those retrofits is they need constant attention and tweaking vs the tormachs which need minimal adjustments .

The best advise I can really offer is to decide which machine you can work on within it's specs . If the 440 doesn't have enough travel then it's not the right mill to have , if it does then you'll have a much more capable and reliable machine to work with

[cndingus]

Pcnc440 twist out of the box , I've never heard of that ? . I pulled my machines out of the crates , dropped them on bases and ran from there . I'd more expect twist out of the other mill .
Tram isn't an issue on the 440 , any time I found tilt in the head it was because the gib needed adjustment . Thats only happened a couple of times over the years .
open loop steppers run perfectly fine and closed loop isn't going to get you any further ahead or closer to servo run .

You can squeeze a bit more out of the y than what it is set to , and the x can be pushed to 12" by replacing the ballscrew with a longer one .

Don't be fooled by the .25hp difference in the motors because they are completely different setups . Those companies claim big tools but the reality is they can't handle them

I ran retrofit mills for a few years before buying my 440's and I'll never retrofit a mill again . My g0704 is laying in pieces on the floor and I highly doubt it won't go to the scrap yard in the next yr or so and the others are rusting in my garage . The problem with most of those retrofits is they need constant attention and tweaking vs the tormachs which need minimal adjustments .

The best advise I can really offer is to decide which machine you can work on within it's specs . If the 440 doesn't have enough travel then it's not the right mill to have , if it does then you'll have a much more capable and reliable machine to work with

Thank you. I think that's the crux. I just don't know if 6" in Y is enough for me... I'm a hobbyist and use this thing to make parts for... well whatever random project I'm working on. So it's really hard to forecast whether or not I need the additional few inches of Y travel. Having never built a retrofit machine I don't know what the problem areas are... I figured since the PM machine comes with their ball screw kit it may be more reliable, but I suppose it's still a retrofit at the end of the day. I think the spindle is really the biggest concern there with the RPM anyways. I do wonder which machine is more rigid; the 440 weighs 80 lbs more according to the spec sheets I've been reading so not a significant difference.

The Tormach pre-sales rep told me that they may have some twist out of the box, necessitating a shim or two under one of the feet on the casting to bring it back such that the bed is a consistent 0.001" across. A quick google search brought mixed results on this so maybe he was being overly cautious with me? The honesty was appreciated though.

[metalmayhem]

rigidity isn't necessarily due to weight even though thats often a factor , in this case it's not . The tormach was built well and they have a good casting design . The other is a hobby mill/drill pumped out of a mass production factory and they aren't as sturdy built .If the tormach has twist then I can assure you those chinese mills will have much more
In my opinion their cnc kit is over priced as is the mill .
As far as spindle speed goes you could belt it and get more rpm . The problem with that is your spindle torque will drastically drop and thats where the 440 will by far outshine the bigger motor .

As I mentioned I've got a g0704 , not that exact mill but another equivalent brand with a belt driven 1hp spindle , as well as a few x2 converted mills which are all dead in the garage but one . I made a lot of parts with them but in the big picture they are all junk and were a pita . I machined long enough in my life to know how to make them work for what I needed, but even with that the scrap pile was higher than I'd have liked , and now it is almost non-existent . Also the quality and appearance of my parts are far greater than they were

If your going to go the retrofit route then I suggest looking at a g0704 and one of the kits that are available online , it would be more cost effective . If your only doing small parts in aluminum then they'll suffice . You'll just need to learn the limitations and quirks and work within them . I don't know what difference there is between the 704 and the one your looking at but it's worth comparing them . If you go with a retrofit then be prepared for constant adjustments if your running it a lot . They can get the job done but they aren't ideal .

This is my experience with the 2 differences and my opinion for myself is pretty firm . Those turd mills built a company so I don't have a total sour for the retrofits , it's just when comparing those to my tormachs then the junk factor sets in . One thing may work for some and not others so I'm not going to try and convince you one way or the other . Either way a guy looks at it - it's a good chunk of change and a guy has to make the right decision

An alternative is to watch craigslist or ebay for a decent deal on a larger tormach or something similar . A novakon torus pro was posted south of me on cl earlier today for $1500 , those deals rarely come up but good deals do happen every so often

[metalmayhem]

I took a better look at that pm , it's definitely more machine than the g0704 . It's too bad there aren't better videos showing it in action , the aluminum cuts were painful to watch . I think the first thing I'd do is modify that spindle to something much faster

[cndingus]

I took a better look at that pm , it's definitely more machine than the g0704 . It's too bad there aren't better videos showing it in action , the aluminum cuts were painful to watch . I think the first thing I'd do is modify that spindle to something much faster

Yeah the PM728 appears to be a much better quality machine which is why I'm even considering it. And the work area is closer to the Torch 770 -- I'm really worried about the 6" Y axis on the 440 otherwise it would be a no-brainer.

[metalmayhem]

something to consider is that a 440 with a chip pan and control is $7700 the 770 is $9100 with the same bare bone options , which is only the difference of 1400 . If you could stretch it then I think you'd probably be much more satisfied . When I bought my first 440's the price was 5k and the difference within my budget at the time was 3 440's or 2 770's . The price gap has closed in since then and the price difference makes the 770 much more appealing

[phomann]

Yeah the PM728 appears to be a much better quality machine which is why I'm even considering it. And the work area is closer to the Torch 770 -- I'm really worried about the 6" Y axis on the 440 otherwise it would be a no-brainer.

A couple of things to consider.
PathPilot is a very robust CNC control software with an intuitive user interface. It works out of the box.
On the PM mill, check the amount of movement in the positive and negative direction when the center of the table sits under the spindle. You will most likely find that it’s not 3” of movement either side if the spindle.
There will be more movement when the table moves away from the column and less when moving towards the column.
It’s a real pain when you need to use the full Y-axis travel as you can’t center the stock on the table. It needs to be offset and hang over the tabs in the +ve Y direction.
The impact of this is that although the Y axis has 6” of movement, it’s not all useable.

Some people add a 2” spacer between the spindle head and the column to correct this, but it impacts the machine rigidity.

As to the Tormach machines I don’t have one so can’t comment.

Cheers
Peter


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[cndingus]

Hmm, the base 440 is 6500, base 770 is 8700. 2200 difference off the bat. Factor in increased taxes and shipping + lift bar kit (to hoist it) for the 770 and the difference is closer to $3k. Plus I’m not sure how I could build a stand for the 770 given its 800lb weight. But perhaps I could?

All-in for my options, including Tormach incentives, the 440 is $8500 shipped to me and the 770 is $11500 shipped to me. No stand or chip tray for either. The only pricey options I have selected are vices, zero probes, and TTS ER20 tool holders.

It’s a pretty significant price difference, enough I think to push out of my budget. But I’m not necessarily giving up on the idea. The added y and z travels just make sense. I really want the 770 but how I’m going to support it with a stand and how I’m going to afford it (and potentially how it’s going to fit in my garage — gonna have to shove the y stepper into the drywall lol) are the primary concerns for sure.