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  1. #21
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    Default Re: New Power Drawbar.

    Quote Originally Posted by brianbonedoc View Post
    Kvom- the Tts Collet is a std R8 but with the nose ground flat - otherwise it no different. In fact many here use the high quality hardinge Collet and grind it flat themselves
    I believe he was pointing out that a Belleville-based PDB is incapable of easily swapping R8 tools, rather only TTS tools. I believe he is familiar with my PDB for the Novakon machines which will swap either TTS or R8 tools with equal ease...

    Regards,
    Ray L.



  2. #22
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    Default Re: New Power Drawbar.

    Ray - ahh. I think you are right. Is yours available yet for the pulsar?

    Also in your testing did you notice the spindle being off center relative to the head? Mine is shifted to the left (in the casting) by about 0.2 in. It doesn't affect anything other than when I CAD'd up the base plate I had to account for it.



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    Default Re: New Power Drawbar.

    Quote Originally Posted by brianbonedoc View Post
    Ray - ahh. I think you are right. Is yours available yet for the pulsar?

    Also in your testing did you notice the spindle being off center relative to the head? Mine is shifted to the left (in the casting) by about 0.2 in. It doesn't affect anything other than when I CAD'd up the base plate I had to account for it.
    Brian,

    It'll be available for the Pulsar later this year, along with the ATC.

    No, I never noticed the spindle being off-center. But I never looked. The PDB mounting holes are drilled relatve to the spindle centerline, so it doesn't affect me at all.

    Regards,
    Ray L.



  4. #24
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    Default Re: New Power Drawbar.

    Quote Originally Posted by brianbonedoc View Post
    Titanium boy- yeah some stick up out of the spindle. It was that way stock. It really doesnt matter. If u look at the tormach pics all of theirs are above the spindle. It's prob easier to find bellevilles if they are not confined to a specific outer radius. Just remember when u add up the force it should be a bit over 3000lbs but also have a combined stroke of >.060 preferably about .1. My setup has only about 0.064 of travel and works fine.
    The Pulsar Spindle Assembly drawing shows 20 Belleville washers with this pattern. ))(())(())(())(())((

    Did your Pulsar arrive with the number and pattern? If not, what was the original setup? And what was your final washer configuration after finding the 3 stage air cylinder.

    I see how to calculate the total washer force, but how did you calculate the travel stroke?

    I found a Fabco MP4 on ebay, but it only has 2 stages. I think I need your surplus fourth stage.



  5. #25
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    Default 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.



  6. #26
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    Default 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?



  7. #27
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    Default 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.



  8. #28
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    Default Re: New Power Drawbar.

    Quote Originally Posted by brianbonedoc View Post
    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.



  9. #29
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    Default 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



  10. #30
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    Default Re: New Power Drawbar.

    Quote Originally Posted by Steve303 View Post
    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!



  11. #31
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    Default Re: New Power Drawbar.

    Quote Originally Posted by brianbonedoc View Post
    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



  12. #32
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    Default Re: New Power Drawbar.

    Calculations for the washers.

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






    Attached Thumbnails Attached Thumbnails New Power Drawbar.-manual_disc_spring_calculation_program_03-pdf  
    Attached Files Attached Files
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. THREE ways to fix things: The RIGHT way, the OTHER way, and maybe YOUR way, which is possibly a FASTER WRONG WAY!


  13. #33

    Default Re: New Power Drawbar.

    How many turns did you do on the drawbar with the ((()))((())) stack?



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