What The World's Been Waiting For - Yet Another Power Drawbar Design

[Hood]

Heres is a pic of the top of the drawbar and lastly a pic of the quill bracket I made to convert my manual Bridgeport to CNC.
Hood

[simpson36]

Hood, let me just comment that your dedication to this forum is nothing short of amazing to me. Forums are very expensive, time wise, and you spend a lot of it helping people out. Just wanted to acknowledge.

What I can gather form the photo of the drawbar mechanism looks like something similar to what I had in mind, except that using htdraulic power eliminates the mechanical advantage required for an air cylinder. i.e. no scissors. Hydraulics are arguably more expensive (depends really on what you already have aroud the shop) and certainly a lot heavier mass to move around. On the other hand, it will probably perform for 30 years like the day it was installed, save an new o-ring here or there.

The quill drive is a nice clean deisgn and is also what I envisioned as the way to go for a quill drive. Yours is the first I have seen and it looks to be very beefy. I don't know why, but that's what I expected from Hood . . rugged, non nonsense, bullet proof.   

Others have attacked the problem by motorizing the rack, which probably seems logical at first thought.

[Hood]

Simpson
Air over oil can probably get round the expense issue but suppose that depends on whether you have access to cheap air and hyd cylinders, working repairing boats hydraulics are fairly easy for me to obtain, air not so easy but eBay is wonderful
 I was fortunate that this is standard equipment on the mill so no thought at all had to go into it from me thankfully
 Quill versus knee and ballscrew versus rack will always be debated, personally my thoughts are quill with ballscrew for fast work and knee for tool offsets is the best way, well bedmill is the best way but I dont have one and probably never will due to headroom, so thats not an option. The Beaver has an induction motor on the knee so fitting a servo would not be a problem, maybe an alteration to the mount and thats it. It does however just have a leadscrew on it but I am hoping the backlash is linear so comp should work well and the weight will negate any problems with tool trying to lift it I think
 Rack would be, I think,  hard to get any kind of backlash free accuracy from so never considered it, the comp could be used I suppose but then the tool could push and pull it so some form of damping/lock would be needed, again not impossible but would it be worth the hassle?

Hood
 
 

[vmax549]

HIYA RAY, HOW is it going??  Any more news ?? pictures???

(;-) TP

[HimyKabibble]

HIYA RAY, HOW is it going??  Any more news ?? pictures???

(;-) TP

Terry,

Busy with other things for a few days.  I've gotten some re-machining done, and the mount plate fabbed, so I'm close to putting it on for a real test.  My only remaining concern is getting the runout/balance on the guide tube under control.  I need to make a new, aluminum, guide tube, and do it on a better lathe so it's as true as possible.  Any runout/imbalance on that causes chatter on the dog clutch on the spindle, which will cause wear.  I can test it with the tube I've got, but don't want to run it too long.  I may just remove the dog clutch and replace it with a solid coupling, since I never use the backgear anyway.

Regards,
Ray L.

[vmax549]

I did find a source for a BP qc30 spindle shaft that is an extra 6" long at the top(;-) that would give us the extra reach needed for the top mechanism to clear without adding the tube as the springpack would ride directly on the top of the shaft and it would be long enough to clear on all quill operations.

I think there is room inside the shaft to make the adaptor for the claw mechanism (;-)

MIGHT just have to try one. (;-) Can't let you have ALL the fun.

(;-) TP

[HimyKabibble]

I did find a source for a BP qc30 spindle shaft that is an extra 6" long at the top(;-) that would give us the extra reach needed for the top mechanism to clear without adding the tube as the springpack would ride directly on the top of the shaft and it would be long enough to clear on all quill operations.

I think there is room inside the shaft to make the adaptor for the claw mechanism (;-)

MIGHT just have to try one. (;-) Can't let you have ALL the fun.

(;-) TP

Terry,

How many $$$$ was it?

I don't understand how that can work - can you provide a link?  I don't see how it's possible for the spindle to be any larger than the splined part, as that has to pass through the dog-clutch....

Regards,
Ray L.

[vmax549]

The splined part is 6" longer allowing it to stick up above the top .

(;-) TP

[Hood]

are they from a series 1 CNC?
Hood

[vmax549]

HOOD I believe so, I think the cnc version is longer to account for the drive assy for the quil screw.  That should work well for a standard series 1 head. It would leave the top of the shaft out of the top of the machine. You would just need to make sure you got the CNC shaft that has the hole in it.  That woul d eliminate the problem of the wobbly tube as the springpack could mount directly to the top of the shaft.

Then if you coul dhave the spindle machined for the claw mechanism you woul dhave a true tool changer just like the big boys and you coul deven use CAT30 tool holders, just change out the drive lugs to fit the cat30.

Just a thought, (;-) TP