Friday, March 15, 2013

Jig Bore Handwheel Repair

A few weeks ago I told the story of how I ended up with a damaged Kearney and Trecker Autometric jig bore. As the machine sits in the shop I'm starting to get very curious how I might use this machine. Having a horizontal spindle is a very useful item in any machine shop. The question is how can I use this machine and is it worth the floor space it will take up. Regardless of all that I need to fix some of the damage from the previous owner and get it in running condition so I can play with it or trade it for something else.

Fortunately the damage to the machine was minimal. The nice cast iron handlwheels absorbed most of the energy from the tip over. The shafts that the handwheels were on were not bent so I was glad to discover that. I thought about just buying some similar sized commercial handwheels, but on closer inspection I had all the broken pieces of the cool old school cast wheels. This makes for a interesting repair job.
The wheels are around eight inches in diameter. I thought it was weird that they weren't the same diameter. Maybe this in one of the reasons they went out of business? Just looking at them they looked the same but when I measured the OD with calipers there was around  three eighths difference in the OD. At least the center shaft size was the same at five eighths. What was needed here was a fixture to help me align the broken parts and keep everything concentric. Its important that the handwheel run reasonably true and in plane.
A simple plywood fixture was created to hold everything together. I started with the smaller OD wheel so I could re-cut the fixture for the larger wheel if it all worked. I just cut in from the side for the part with the hole. This allows me to squeeze the gap closed to actually clamp the part a little. All that I needed now was the center alignment shaft.
Got lucky that I had some five eighths steel rod around. I turned the end down because I didn't have a five eighths diameter Forstener bit. Forstener bits are the cats meow for accurate holes in wood. I'll pick up a five eighths Forstener this weekend. I hate to be held up by tooling issues.
The handwheel in the assembly fixture. You can see I closed the gap up and shot a couple of screws into the ears to clamp the wheel tight.
I used a mini grinder with a Walter abrasives Zip cut disc to gouge the cracks for welding. The areas I couldn't reach with the grinder I ended up with a carbide burr on a die grinder. The goal here was to get this securely tacked up and do the welding out of my combustible fixture.
 The welding rod I used is Ni-99 TIG welding rod. Its basically pure nickel rod. It works great for small cast iron repair jobs like this.
Once the wheel was securely tacked I could get it out of the fixture. The sequence was gouge and tack until I had all the cracks prepped for the welding. By this time the wheel was pretty warm which is just what I wanted. No need for a preheat on these other than from the tack welding. I don't have any temp sticks but my calibrated bare hand told me the wheel was around 150F when I got to the main welding. Not hot but not cold either.
As you can see the welding came out pretty good. I managed to save a piece of history. Later on I'll grind and finish the surfaces where your hands contact the wheel. Other than that I don't think I'll fill and blend all the welds.

I did do some experimental video shooting on this job. My still camera shoots OK video so I figured I'd try it out. Please comment and let me know if you like the written stuff better than video or vise versa.
There are more video's in this series on my YouTube channel oxtoolco. Check them out. I still have some to upload.

Thanks for looking.

10 comments:

  1. Interesting repair, Tom. I just watched your videos and enjoy seeing the process. Personally, I like a mix of writing and video, you get pluses and minuses from each.

    Are you going to video this project thru completion? I'd like to see the final results!

    On another note, forgive my ignorance, but what's the green turret-headed press behind you in some of the videos? It looks like it has a motor...seems like a useful machine.

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  2. Hi J,

    Thanks for the comment. I want to experiment with the video thing for the very reasons you mention. Right now I have more segments to add to the video documentation of the handwheel repair. Take a look later today for more.

    As far as the green machine in the background its a Burgmaster Turret head drill press. I picked it up at an estate sale not too long ago. It has six spindles that index sequentially when you bring the lever all the way to the top. Each spindle turns a different speed so you can set up a drill, tap, chamfer, sequence. These were very popular in the 60's and 70 for drill press production work. This is the smallest one they ever made. The large ones are monsters.

    Regards,

    Tom Lipton

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  3. I'll keep my eyes peeled for your videos as they appear.

    Very interesting tool. I've never seen one of those Burgmasters in the wild. Do you find it useful? It seems like a great idea, if for a specialized production setup.

    Thanks for your great blog,
    James

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  4. Hi Tom, This is an interesting repair, thanks for the write up!

    I appreciate all the information you provide, along with the very helpfull pictures.
    I liked the addition of the video's. I would suggest using the video's to show some action, such as the welding of the handles rather. Showing details while presenting, doesn't really work with this quality video (it doesn't show without zooming).

    Keep up the great blog!
    jochem.

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  5. Hi Jochem,

    The video is new to me. I only have one camera right now that I'm experimenting with. Hopefully I'll get better and find the optimal spots for the camera to catch the action in more detail.

    Regards,

    Tom Lipton

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  6. Tom,

    Just saw your Burgmaster video--THANK YOU. Cool little machine. Now I have to keep my eyes peeled for these things.

    I'm enjoying the videos during my Solidworks design breaks.

    Best,
    James

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  7. Hi James,

    No problem. Old school still rules! Maybe one of these days I'll take the turret head apart and see how this thing is put together.

    Regards,

    Tom Lipton

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