Power Drawbar for BP

[kroll]

Afternoon guys,well I am slowly finding my way around the forum have to say its fantastic.So many good ideals for projects that be good for this beginner.Guys I been watching some Youtubes and did some searching on how to make a power drawbar for a mill,well I want to make this my next project but have some questions that I just did not find answers to reading others post on their Drawbar.I want to make one with the pneumatic cylinder that will pull the impact down but I can't find any kind of details on what kind cylinder to look for.Several have said they purchase theirs off ebay but they are there by 1000's.Guys what do I need to look for,since its small guessing it ready don't need something big.Maybe 1" dia or maybe 1.5 dia cylinder with a 2" stroke?Been collection little bit aluminum for this project so still in collecting stages.Guys if you know of any links or what I need to make this work please share to any other post or websites or even to cylinder that you use for yours.Thanks guys for some guidance

[high-side]

Do you have a small or large mill? There is plenty of free info on power draw bar design on cnczone

[kroll]

Thank you for replying,I wish I would have remember that info would be helpful.Its a BP w/VS I think from the early 70's.Thanks for the cnczone info going to check it out.

[J.Ramsey]

Here's a link to over at SFT forum on building the Pneumatic Drawbar.
About the second/third page I posted several close up pictures and a video of it in use.
For the cylinder I recommend a Bimba 171D iirc it is a single acting spring return with a 1" stroke and about a 1-5/8 bore Still works today some 14 years later,worn out several butterfly impacts but their easy to change.



https://www.shopfloortalk.com/forums...ad.php?t=40386

[kroll]

Thank you J Ramsey that is an awesome design which I am going to try and copy it.Out all the Youtubes that I watch on building these I love your ideal of having the return spring.Thanks for the posting the details on the actuator going to check out ebay see if I can find one like yours.Looks like its about 1.5 dia cylinder or maybe 2" cylinder.You give me the numbers so going by that.I also like how you done your switch for fwd/rev having the fittings on the edge instead of on back side,I guess call that cross drilling?I did have to go back and look at the pic with the vent hole(correct?) that is drill in the switch.Now going to order some aluminum and find the actuator run it by here make sure its the correct one.I am excited and glad I come across this forum.
Edit-I see its a 1 5/8 cylinder

[J.Ramsey]

kroll, I got up on a ladder and checked this morning it is a 171 #NK.

[kroll]

Thanks you for going through so much trouble,I just email bimba to see what the replacement is for that model.I did google it and also look on auction site but no exact replacement so checking with Bimba. I sure like the spring return which I think I found out that its 7lbs for 171P but can't find the specs on that one either.So see what Bimba can come up with.

[kroll]

I restricted the air on the tightening cycle to about 25 ft. lbs because those butterfly impacts seem to have more poop for tightening than they do at loosening.
J Ramsey how did you do this,I look over the pics but I just can't spot this.love the post on shopfloors
Found my answer just read few more post found 3/16x1/8 tubing.
Email from Bimba is that a 171P is the replacement so I be ordering one this weekend and some of my aluminum bars came in today 3/4x2"

[kroll]

Well guys I have finally started on my Power Drawbar,which is a pretty good challenge for me since I am a beginner at the lathe and mill.So my game plan is to try and follow J Ramsey design and keep it compact but works and will work over the yrs.J Ramsey said that his has lasted for the last 14yrs so that what I'm shooting for and will put me at 80yrs old by then I have two of these 6" disk one will serve as the base which will bolt to the BP then this one in pic will have the impact and the actuator mounted on it.And I have to say that laying out these holes was a big challenge cause math is not one of my strong suites,but being hardheaded and determined is.So here I am so far,if anyone has any suggestions I am all ears I don't want to make any silly mistakes.

[thehomeengineer]

Hi Kroll
Below is a link to the power draw bar I made a few years ago and is still working OK today. These are a great addition to the mill and I know most home workshops are not concerned about how quick a job can be made but these certainly make the task of changing tooling very easy (and quicker)
Pneumatic Power Drawbar for Bridgeport Mill
Hope this is of interest
The Home Engineer