Machine Shop

[BlueScarecrow]

I need the 5 bolts put back into the periphery of my brake drum so the speedometer will work again. I've called 20 machine shops here in town and no one can do it. The old ones broke off, but there's plenty of meat left for 5 new holes every 72 degrees. Anyone know of a machine shop here in town that wants the job.

CliffCo Heavy Equipment can do the job, but they want $400 for 4 hours of work. If you have an Indexer and an End Mill it would take about 20 minutes.

Any help would be greatly appreciated.

Thanks!!!

[luvrbus]

Have you tried Baker Machinery in Higly 480-988-1188 speak to Mark or Tom lol better speak to Mark,Tom can be a little cranky comes with age 

[BlueScarecrow]

I asked for Mark or Tom, but Jesse came on the phone and wants to give me a quote. Jesse also wanted to see the drum before he quoted me. I tried to explain to him that it was just a big brake drum about a foot and a half across and about 8 inches deep. For some reason he couldn't picture that, so I sent him an email with a picture.

Thanks Clifford!

[chessie4905]

    You should be able to drill the holes and tap them yourself. It is not that difficult. You can do the indexing with a divider and play with the setting till you have the 5 hole marks equidistant from each other. That is how we did ours.

[BlueScarecrow]

I may give that a try. My friend has a hand-held drill press that he uses for his model work.

I think I could rig up something to keep it perpendicular to the edge of the rim.

Math-wise, I'd have to figure out the circumference and divide that by 5.

That's a great idea.

Thank you!


Mike

[dickegler]

Mike,

could you just move an inch to the right,or left, of the 5 broken bolts?  I don't think the spacing would be that critical, and hand drill the new holes?

Dick

[chessie4905]

   Use a ruler or small square to make the holes close to perpendicular. They aren't that fussy. Don't try to make the holes any deeper than 3/8 to 1/2 inch. Use new bit sized for proper tap and use tapping fluid. Do NOT force tap as it is hard and  some what brittle. Take time and frequently back it up 1/4 to 1/2 turn. Be careful when you hit the bottom of hole; that is when it is easy to snap off. Forget about trying to drill out or remove  a broken tap without proper tools. 

[krcevs]

Make sure you use a bottoming tap. That way you do not snap off the tap when it hits the bottom of the hole.
Bottoming taps are designed to run threads in a blind hole. Standard taps are not and the taper will cause them to bind and break off when they hit bottom. HTH

Ken

[luvrbus]

Why not drill the old studs out I believe those are grade 5 driven in not threaded

[BlueScarecrow]

Thanks to all for your help.

I was going to draw this out on paper first.

C = 2 π r, should get me close to the circumference and then divide that by 5 and I should have it.

I know about tapping. Found a wonderful lubricating fluid called "Tap Magic"... Visit: http://www.tapmagic.com/
It works a thousand times better than oil.

The original bolts were 1/4" coarse... I believe 1/2 deep.

I'll probably stick with the same 1/4" coarse thread machine bolt 3/8" long. No need to go any deeper as the sensor is only looking for the head when it passes by.

I'll put "No Seize" on the threads too. Big fan of "No Seize".

This bus is 32 years old. If I had an end mill I could have gotten those old bolts out; they were rusted in there pretty good.

Thanks again!


Mike