New Power Drawbar. - Page 3

1. ## Re: New Power Drawbar.

I can't recall my original configuration.

My current one uses 12 bellevills each with 0.016in of travel.

When stacked like this ((( you only add the force (eg 1000+1000+1000)

When Stacked like this () you add the travel together not the force (so 0.016+0.016)

Mine are stacked like this ((()))((())) so it's travel is 4x 0.016 = 0.064 and the force is 3x 1070lbs.

I hope that makes sense.

2. ## Re: New Power Drawbar.

Brian,

Thanks for the reply. Between your explanation and some extra research I think I now see how the Belleville washer calculations work.

So if I understand correctly, the original Pulsar washer stack of ))(())(())(())(())(( has ten series with each series having two in parallel. This would give a travel of ten times and a force of twice that of a single washer.

I checked on Novokons website and they want \$2.00 per washer and they note that a complete set is 20 washers. Of course there is no way of knowing which washers Novokon used, and so no way of knowing the travel and force.

In actual use you would compress the washer stack by some amount to give an adequate spring pressure, yet still leave enough room to squeeze the washer stack further to release the tool?

Does your setup, or for that matter the original Pulsar setup, mean you can only use TTS tools or can you remove enough stuff to enable occasional R8 tooling?

3. ## Re: New Power Drawbar.

It's pretty easy to unscrew the drawbar from the R8 collet and screw in any other R8 tooling. It takes about 30secs.

The bellevilles I used were from Mcmaster. these ones: https://www.mcmaster.com/#9712K435

If I didn't have to fit them inside the spindle (max diameter of about 1"), then there are many more choices at mcmaster.

4. ## Re: New Power Drawbar.

Originally Posted by brianbonedoc
It's pretty easy to unscrew the drawbar from the R8 collet and screw in any other R8 tooling. It takes about 30secs.
I agree without having to remove the Lever Draw Bar it would take less than a minute to remove the R8 Collet from the drawbar.

5. ## Re: New Power Drawbar.

Finally back to my PDB build. Received my cylinder today. It did take a little longer than I had expected to receive the cylinder (Fabco MP4X1X31FF). Had to order it through a distributor as you can not order this cylinder on-line. I had hoped to find a used one on-line but gave up looking and decided to purchase a new one. This cylinder weighs a little more than 9 lbs so it should be no problem for the Z axis. I am using Brian's cad file.

Steve

6. ## Re: New Power Drawbar.

Originally Posted by Steve303
Finally back to my PDB build. Received my cylinder today. It did take a little longer than I had expected to receive the cylinder (Fabco MP4X1X31FF). Had to order it through a distributor as you can not order this cylinder on-line. I had hoped to find a used one on-line but gave up looking and decided to purchase a new one. This cylinder weighs a little more than 9 lbs so it should be no problem for the Z axis. I am using Brian's cad file.

Steve
Steve - just an update. I love my PDB now! I never get any pullout and the rubbing from the lever drawbar is history.
I did add some extra bellevilles, I forget exactly but I have somewhere around 24 of these: https://www.mcmaster.com/#9712k435/=18vu53f

I get plenty of travel and holding strength. I shouldve done this a long time ago!

7. ## Re: New Power Drawbar.

Originally Posted by brianbonedoc
Steve - just an update. I love my PDB now! I never get any pullout and the rubbing from the lever drawbar is history.
I did add some extra bellevilles, I forget exactly but I have somewhere around 24 of these: https://www.mcmaster.com/#9712k435/=18vu53f

I get plenty of travel and holding strength. I shouldve done this a long time ago!
Thanks for the update. Looking forward to the using the PDB. I wish I could order from McMaster. Unfortunately, they will not ship to Canada. I've even tried having items shipped to a USA mail box (UPS Store) they always cancel my order.

Steve

8. ## Re: New Power Drawbar.

Calculations for the washers.

The .rar file was too big to upload, so you need to extract the .xls file

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