2018 POTD Thread Archive

I never though about making my own drill guides...until now :cool:

Robert
 
BGHansen said:
I did a POTD back in May to make a drill fixture for reworking a part at our car assembly plant. Part of the fixture was a couple of hardened steel drill bushings. Well, they’ve been in use for over 6 months at 250 holes per day, or around 50,000 cycles. Finally seeing a little wear in them so remade them today.

Chucked up some 1” drill rod, faced, and turned a shoulder at 0.625” diameter 0.875” long. I used a grooving tool to cut some ridges in the outside of the bushing. These will be Loctited into an aluminum holding fixture, think the grooves will help the Loctite get a better grip.

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Cut off the bushing on a band saw. Could have parted on the lathe, but with drill rod I usually go the saw route.

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Re-chucked with the rough side out and faced. Center drilled, and drilled a ¼” through hole. The final size would be about 0.006” over 12 mm which is slightly over a 15/32” drill. Ran a 15/32” drill bit through which was 0.004” under 12 mm. Finished drilling with a 12 mm drill, then bored to about 0.006” oversize.

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The drill fixture is used to knock holes through a plastic part, so we are using a brad point drill bit. I put a little taper on the first 0.15” of the hole with a 2MT ream, then countersunk the hole.

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On to heat treating. I picked up a 110V Thermolyne 2025 muffle furnace (anyone know why they call them a muffle furnace? If I was to hazard a guess, there isn’t any forced air so maybe the sound is muffled?) and used that to heat the bushings to 1500 F.
Bruce
Click to expand...
A muffle is a receptacle in a furnace or kiln in which things can be heated without contact with combustion products. Although most muffle furnaces are electrically heated, at one time, they were fired with petroleum products.
 
rwm said:
I never though about making my own drill guides...until now :cool:

Robert
Click to expand...
Hi Robert,

Naturally, depending on the project they can save a lot of time. Look at some of my posts for Erector set parts. One in particular is part# DT one-hole coupling. My competition and I used to make them the same way. Chuck up some 5/16" brass, center drill and drill an ~0.550 deep 11/64" hole in the end. Then part to length. Flip the part and file a dome/radius on the end. Then to the bench for some layout work for an 11/64" cross hole and a 6-32 tapped hole 90 deg. from the cross hole. We could make 4 to 5 an hole, sold all we could make for $7 each.

I now chuck up the 5/16" brass but don't center drill before doing the ~0.550" deep 11/64" hole. Instead, I slip a drill bushing over the brass rod, bushing has an 11/64" hole through the center which holds the drill bit on center. Saved a tooling change step. Then I slip another hardened drill bushing over the 5/16" rod which has a guide for both the 11/64" cross hole and the 6-32 tap hole. Do the 11/64" first with a 110V hand drill and pin the bushing in place with the shank of a drill bit. Rotate the lathe chuck 90 deg. and drill the 6-32 tap hole with a cordless. Pull the pin, remove the drill bushing. Power tap the 6-32 hole with a second cordless drill. The drill bushing is cut to the length of the part, made a parting tool which has the end dome profile on it, so position the parting tool based on the drill bushing and part. Clean up the nib on the end with a Scotch-brite disk on a bench grinder. Now comfortably make 22-25 per hour.

Bruce
 
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RJSakowski said:
A muffle is a receptacle in a furnace or kiln in which things can be heated without contact with combustion products. Although most muffle furnaces are electrically heated, at one time, they were fired with petroleum products.
Click to expand...
Thanks RJ!
 
Added a light to my plow, and modified the bracket holding the winch switch (which lifts/lowers the plow) and now the light on/off switch so that it can be more easily removed when the plow is removed from the drive unit and replaced with the mower front-end (as the winch switch and wiring harness was damaged this summer while I was mowing with it, so now I'll remove it from the unit).

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Also fixed up some of the lights on my trailer. I had got them all working, but some of the wires were hanging down and exposed to spray from the tires, and came apart from this, and perhaps from being dragged through snow as well. I fixed the wiring, and bought/installed some body clips to hold the wires up and out of the way.
 
francist said:
Finally got around to making an adjustable cutoff stop for the bandsaw....

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....after using the saw for almost 15 years without one. :rolleyes:

-frank
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I like the stop. My saw has the original stop that came with it. I seen a stop collar on YouTube so I machined a collars.


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