Page 2 of 2
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 13, 2019 12:51 am
by ScotY
For an encoder, take a look here:
viewtopic.php?f=20&t=1944
That seems like the easiest and most elegant solution to me.
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 13, 2019 9:08 am
by Muzzer
The easiest and most elegant solution for spindle speed would be if the Acorn CNC12 software could take account of the ratio between the motor and the spindle, so you could use a motor-mounted encoder. There are loads of machines where a spindle encoder is a royal PITA and although the solution in the link is one way round it, it's beyond the capability or appetite of most users. This issue affects both my Bridgeport conversion and my Shizuoka VMC. Ironically, the ancient (1980s) controller fitted to the Shizuoka was able to figure out the spindle speed from the motor speed and the Chinesium controller that I used before the Acorn also had this as a std feature. For the Acorn, it would "just" be a matter of accepting it would be a compelling feature and implementing it in the PLC software. I'm surprised it hasn't happened yet, given the popularity of the Bridgeport head on so many machines. I'm guessing so much water has passed under the software bridge that it would actually end up an unpalatable task now.
A robust ATC that provides some feedback to the controller requires more IO than is left over on most conversions in my view, so I plan to await the expansion board before taking that any further on my machine. Although it's possible to send up / down type controls to an ATC, you really want to know what tool is actually presented, rather than hope the tool selection worked without issue.
Any update on the expansion board timing?
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 13, 2019 11:29 am
by briuz
Muzzer wrote: ↑Sat Jul 13, 2019 9:08 am
The easiest and most elegant solution for spindle speed would be if the Acorn CNC12 software could take account of the ratio between the motor and the spindle, so you could use a motor-mounted encoder. There are loads of machines where a spindle encoder is a royal PITA and although the solution in the link is one way round it, it's beyond the capability or appetite of most users. This issue affects both my Bridgeport conversion and my Shizuoka VMC. Ironically, the ancient (1980s) controller fitted to the Shizuoka was able to figure out the spindle speed from the motor speed and the Chinesium controller that I used before the Acorn also had this as a std feature. For the Acorn, it would "just" be a matter of accepting it would be a compelling feature and implementing it in the PLC software. I'm surprised it hasn't happened yet, given the popularity of the Bridgeport head on so many machines. I'm guessing so much water has passed under the software bridge that it would actually end up an unpalatable task now.
A robust ATC that provides some feedback to the controller requires more IO than is left over on most conversions in my view, so I plan to await the expansion board before taking that any further on my machine. Although it's possible to send up / down type controls to an ATC, you really want to know what tool is actually presented, rather than hope the tool selection worked without issue.
Any update on the expansion board timing?
Hello!
What is this expansion board? It sounds interesting!
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 13, 2019 11:35 am
by martyscncgarage
Still waiting on software to catch up for the I/O Expansion board.
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 13, 2019 11:39 am
by tblough
It's easy enough to calculate the spindle speed from an encoder anyplace in the drive system. The reason the encoder needs to be 1:1 with the spindle is so there is exactly ONE index pulse every spindle revolution at the exact same spot in the revolution EVERY time. This is what enables peck tapping.
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 13, 2019 3:53 pm
by Muzzer
Yes, I get that. It seems the usual solution to that consideration is to enable "full" rigid tapping with the ability to do peck (full withdraw) where there is an index signal from the encoder - and a slightly less capable version where there is no index. For the latter, you need to gear the spindle to the Z axis but this doesn't actually require an index. Even if this required a tension compression head, it would be a pretty useful function.
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 20, 2019 1:45 pm
by SCYBUCK
Just a random thought that a GECKO G540 operating at 48 VDC have the gumption to drive a used Tormach? CNC 12 is a given for this application. I have been looking at used Tormach equipment on the obvious eBay. Not gonna pay a stupid price for a used Series 2 or 3 Tormach. DOes a Tormach devalupate at the same rate as a Ford or Chevy?
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sat Jul 20, 2019 4:06 pm
by Dan M
SCYBUCK wrote: ↑Sat Jul 20, 2019 1:45 pm
Just a random thought that a GECKO G540 operating at 48 VDC have the gumption to drive a used Tormach? CNC 12 is a given for this application. I have been looking at used Tormach equipment on the obvious eBay. Not gonna pay a stupid price for a used Series 2 or 3 Tormach. DOes a Tormach devalupate at the same rate as a Ford or Chevy?
I was looking for a used one for awhile with no luck, for some reason those things are almost the price of a new one if you can find one at all. I gave up trying to find one since in my opinion they are overpriced to begin with. I guess since they have done a great job marketing them they have excellent resale value. It's a tough one since for the price you could buy a used fadal or something similar but you need a forklift and a lot of space for one as well as power to run it. I was looking at Syil and Skyfire since you can get them customized and I honestly think they are nicer than the Tormach and it looks like you get alot of machine for the money. As far as the G540 goes I would think it would be fine, but the GR214v drives are way better and will handle more voltage.
Dan
Re: Upgrading Tormach PCNC 770 to Acorn
Posted: Sun Jul 21, 2019 2:49 am
by DocsMachine
SCYBUCK wrote: ↑Sat Jul 20, 2019 1:45 pm
DOes a Tormach devalupate at the same rate as a Ford or Chevy?
-Cars and trucks get devalued mainly because there's an open and obvious odometer, and it's well-recognized that the vehicle will need expensive repairs starting at or around X miles, and secondly because the manufacturer comes out with a new model every year.
Few machine tool manufacturers release an upgraded model once a year- you might see used Tormach prices come down a bit when the MX models are finally dropped, but really, barring potential issues with the older software or something, the older machines are very nearly just as capable as a new machine today.
Throw in the current demand on machine tools in general, especially the smaller, more affordable "home shop" type stuff, and yeah, Tormachs are holding their values well.
Doc.