TTS toolholding recommendations
Hello folks,
I'm researching toolholding options for my PM25-MV while it's on its way, and a lot of people seem to prefer Tormach's TTS for CNC work on these machines (G0704 etc). However, looking into brand name vs knockoffs it seems that while the knockoffs (igstools etc) are about half the price, their quality isn't that consistent. This makes me think of the old warning "buy nice or buy twice".
I realize the PM25-MV isn't the pinnacle of craftsmanship, but I'd like to get the best out of it that I can, which makes me wary of cheaping out on toolholding. Looking at the variability in the knockoff stuff made me wonder about the brand name parts, since I couldn't find any information on Tormach's site. I reached out to their tech support people and inquired about the runout specs of their R8 to TTS adapter as well as their TTS ER collet chucks, and was told that they don't have an official spec for runout, but the tech said that he'd expect it to be about 0.001" to 0.002" depending on distance from spindle nose. This was followed by instructions on how to use ER collets.
These numbers basically demolished everything I'd been reading for the past few days, as others have reported runout much lower than this for the unbranded mystery parts. My concerns about buying "quality" ER collets ($100/set) vs unbranded ones ($20/set) seem rather moot too. What good is <.0003" runout collet on a 0.002" chuck?
Am I barking up the wrong tree here? Is the sort of precision I can expect from a PM25-MV not deserving of these sorts of concerns? Or is my enthusiasm for quick change tooling getting the best of me, and I should just stick with R8 collets if I want better precision?
Re: TTS toolholding recommendations
Anytime you start stacking tool holding the tolernaces can go up. Say your R8 3/4 collet isn't perfect. Now add a TTS tool holder and now you have the already imperfect R8 collet plus whatever error is in the shaft and taper of the ER collet. Now add an inch of tool stick out. It doesn't take long before the TIR gets out of hand. .001 or .002 on a 1/2 cutter. No big deal. The cutter will wear a bit quicker and you make adjustments to deal with the oversize cutting. However put in and 1/16 cutter and you'll break them with regularity.
Even on my name brand TTS collets I took the time to measure and mark them so I could index them in the R8 collet to get the least amount of run out. Nothing is perfect.
Re: TTS toolholding recommendations
HInt...
Tormach is getting them from the same place. They aren't manufacturing TTS tool holders in the states.
The choice to go with TTS tool holders is sually related to whether you plan to CNC the machine and perhaps add a tool changer. There is no reason to use them if the answer is no.
Re: TTS toolholding recommendations
Yeah, definitely stick with standard R8 collets if you want to minimize runout.
That said, I machine some pockets that were +/- .00025" using the "off brand" TTS holders just two days ago. I was pocketing seven hardened steel gears using a .25" 4 flute carbide end mill. All but one were +/- .00025", the one that was off ended up a crash because apparently the plug wasn't making good contact on the X axis driver...
This was with a G0704.
Runout sucks, it's hard on end mills, but if you do your homework you can deal with it.
