PDB questions.

[TXFred]

Tonight I had the power drawbar removed from my mill, and I noticed that my drawbar only threads into my collet by about five turns. The threads are starting to show signs of damage from having to spread the clamping force over a small amount of threads.

I'm wondering if I've got an oddball drawbar. I would be grateful if somebody here would take a tape measure to their 1100's drawbar and let me know what they get. For comparison, my drawbar is 11.5" long from the shoulder to the end of the threads, and 12.25" from end to end.

Also, is there a maximum air pressure for the power drawbar? The manual says "90 PSI minimum" but doesn't list a max. My compressor goes up to about 150, and I don't want to damage anything.

Frederic

[Wog]

I don't have Tormach's PDB, but if you use the original bar with it, mine measures close to the same (within 1/16"). Series 1 machine.

[rowbare]

This is from the blurb for the compressor Tormach sells. Of course this refers to the tank pressure not the regulated output. I would take from this that the to be safe the upper pressure should probably be around 115-120 psi.

"Oil-free pump has factory preset start (95 psi) and shut-off (116 psi) pressures for worry-free power draw bar operation"

bob

[TXFred]

I don't have Tormach's PDB, but if you use the original bar with it, mine measures close to the same (within 1/16"). Series 1 machine.

The PDB uses a different drawbar that is slightly thinner, so it can fit the spring washers. But the overall length is the same between the two, so your measurement tells me I have the right drawbar. Thank you.

Bob, thanks for the compressor info. I didn't think of looking at that. I'll set my regulator to 115 and see how that works out.

Frederic

[MichaelHenry]

Keep in mind that Tormach considers the TTS-R8 collet and drawbar to be wear parts that should be replaced periodically. At $21 and $17 each, respectively, it's not too painful to do so once in a while. Tormach also recommends using anti-seize on the draw bar threads, I believe.

Mike

[TXFred]

Well, this is interesting. After I posted this thread, I also gave Tormach a call to get their opinion. Nobody answered, so I left a message.

I got an email back from Tormach yesterday evening.

"Frederic,



I just listened to the voice mail you left with us last week regarding drawbar thread engagement. We had a few of these sneak past QC, we will send you a drawbar of the appropriate length today. I apologize for the inconvenience."

It's in the mail now, and should arrive early next week. I'll do a comparison when it comes in.

In the meantime, I trimmed back the shoulder on my existing drawbar, and got a couple more turns of thread engagement out of it.

Frederic