I got tired of the 11mm wrench pretty quick so I took inspiration from around the web and made a ugly prototype drawbar. I am super happy with the results. Next on the list is to machine a nice combo bracket for the the drawbar and encoder and some cable/hose management.
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Made a Power Drawbar for the PM728
- Thread starter GB21
- Start date
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- Jan 26, 2021
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- 344
That looks like it works consistently. Nice
- Joined
- Dec 26, 2015
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- 2,079
Looks great if you're comfortable with TSS toolholder for everything. I like it.
First failure.I was running a 3/8 endmill pretty hard you can see the angle in the bottom of the pocket where the tool was pulling out. Good thing I caught it before I had a catastrophic failure. The working load of the spring washers is 1890lbs. I watched a video saying the tormach machines are running 2700lbs I am going to try to get closer to that and see what happens.
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- Dec 26, 2015
- Messages
- 2,079
Not sure if you've seen this, but at 1:40 in the timeline he's dealing with the Belleville washer pull power issue:
- Joined
- Jan 7, 2016
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- 3,279
What size of air cylinder did you use on that? I have a number of them lying around...
Fabco 4" 2 stage. It barely fits without modification, I actually had to remove the fan cover from the motor to center the piston. A multi stage cylinder is a must in my opinion. Here is a chart I found useful when trying to figure out what size I needed.
Sorry for the late response I have been a little busy. Mcmaster springs # 9712K436.
I used 3/8" b7 threaded rod for the mount with aluminum tube I found in my scrap bin.The shoulder bolts are 5/16" Diameter 1/4"-20 Thread with 3d printed spacers. The other side I used 1/4" allthread with nylon-cap locknuts. For the drawbar I used grade 8 allthread with double high strength locknuts. (Too lazy to get the welder out). For a switch I am using a cheap foot pedal I picked up on amazon for like 18 bucks (tailonz 4F210-08) works great no leaks yet.
I was trying to keep everything simple in case anything did not work. Turns out everything is working perfect and I have not had to make any changes yet although like I said I will be remaking the shoulder bolt mount a little nicer and to fit a encoder and add more room for the belt.
I used 3/8" b7 threaded rod for the mount with aluminum tube I found in my scrap bin.The shoulder bolts are 5/16" Diameter 1/4"-20 Thread with 3d printed spacers. The other side I used 1/4" allthread with nylon-cap locknuts. For the drawbar I used grade 8 allthread with double high strength locknuts. (Too lazy to get the welder out). For a switch I am using a cheap foot pedal I picked up on amazon for like 18 bucks (tailonz 4F210-08) works great no leaks yet.
I was trying to keep everything simple in case anything did not work. Turns out everything is working perfect and I have not had to make any changes yet although like I said I will be remaking the shoulder bolt mount a little nicer and to fit a encoder and add more room for the belt.
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