ACER 5HP Milling Head Threaded Draw bar to stud puller conversion. Where to start?

Hello everyone,

This is my first post on this forum though I have followed the discussion here for some time, hopefully, I can pull it off without making any terrible faux-pas.

The pneumatic power drawbar just gave up on one of my mills gave up the ghost and I would like to replace the threaded/impact system with a stud puller, pneumatic or hydraulic. The head is ACER e-mill 5HP that I replaced the original with and it has a Cat40 tapper. A while back I did a bit of digging on the web and haven't seen much in the way of retrofits or standards for that matter.

I would appreciate any guidance the members of this forum have to offer with regards to such systems, standards, or sources for such equipment.

As a fun bit of back story, I ran out to find this when I heard the mill making a terrible noise from across the shop while one of the guys ran it. Turns the drawbar doesn't tighten up all the way when the power drawbar looked like this on the inside. Happily, no greater disaster occurred.

Regards,
Julian

Why not buy a new one from ACER? ACERonline

Also you may know what your asking and the photo means something to you, but it's difficult to understand what your asking. A stud puller? Can you show us a photo or drawing of what you mean?

The power drawbar system I was using previously looks like this



The existing system uses a Bridgeport style drawbar to thread into the cat40 tool holders where I would like to replace the drawbar and with a system that grips a stud that is threaded into the tool holder instead.

The pull studs I'm referring to look like this.



Thank you for your reply.

Richard King said:

Why not buy a new one from ACER? ACERonline

Click to expand...

As far as I can tell looking through their website they do not provide anything of the sort. Likely if it's a conversion that can be done there will be no direct fits. It seems like the system is not typically done as a retrofit but rather as part of the original machine. I'm just hoping that there is a way to make it work from some other available system.

Mach-1 Systems - R8 Quick Change Tooling for Knee Mills & Bed Mills quick change tooling. converted draw bar for r8 to pull stud.

I think I know what you are asking. You want a VMC style tool holding system. You want a spring system under tension (Belleville washers) that uses pull studs.
Your machine has a quill, looks like a spline? In the pic?
The quill complicates the system. The quill and it’s drawbar move up and down. The Mach-1 system is an example of what you want, but is for R-8 only(I’m quite sure) and provides small drawbar tension due to small springs.


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Don't think a quill presents any big problems...Deckel and Maho on their early CNC's had power draw bars with pull studs and sensitive quills on both the horizontal and vertical spindles...
The real issue is inside the spindle....
In order for a pull stud system to work you must have a section in the spindle internals ,just above the end of the tool holder pull stud that acts as a cam to allow the gripper fingers to open when the
draw bar is extended and when retracted to pull the fingers closed.....
On most machines this section is shaped sort of like a venturi. The long taper allows the grippers to spread open and release the tool when the draw bar is extended...when tightened, the taper closed the grippers over the
pull stud gripping same as the tool is pulled hard to the spindle taper...

Without this shape inside your spindle the gripper setup will not function....
Further there must be room on the spindle ID to allow for the grippers and their opening.....



Cheers Ross

Yes this is exactly the type of system I was referring to. And you are absolutely right, I had forgotten to check if there is room for the collet to expand in the taper, which is unlikely. I suppose I might be able to modify the tool holders themselves and install some hardware that would allow the collet to operate as intended. I really wanted it to be feasible but it hardly seems worth the while.

Even if I managed to modify all of the shorten all of the tool holders I'm still unsure as to how to apply the tension while the spindle is runnig. Anyone know how this is accomplished in the haas systems?

In the Deckel setup there is a rotary seal between the output shaft of the hydraulic cylinder and the draw bar. In that system (as with most) the clamping force is supplied via
springs (belville washers) and the release is carried out via hydraulic cylinder on top of the total package.
The cylinder is stationary, to the quill...quill movement is handled by flex hoses to the cylinder....

Cheers Ross