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I need to get screwed.

Schurkey

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I've been on a four-month quest to find a chuck screw for a Mac AD850 reversible half-inch air drill. This would be a reverse-thread, flat-head screw. I still need to put the fragments against a thread-pitch gauge to see what thread size it is.

If the drill wasn't reversible, there'd be no need to hold the chuck to the output shaft with a screw--the chuck would just self-tighten on the main threads. But since the drill turns backwards, a REVERSE THREAD screw keeps the chuck tight.

Having a reverse-thread (Left-hand) screw on a reversible drill is common as dirt. Problem is, no one around here carries reverse-thread screws.

Of course, I tried the local Mac Tools dealer. He prints out the parts list for an AD850/AD800 air drill. The Mac Tools part number (was) 70217. He says it's discontinued.

I call Mac Tools. The person in Customer Service tells me that 70217 is discontinued, but it's been superceded by VKG70217. I gave them my credit card info, and told them to ship three of 'em to me.

A month later, I still don't have my screws. I e-mail Mac Tools; and several days later they tell me that VKG70217 is discontinued, and my order was cancelled. Gee...thanks for contacting me with the news of the cancellation!

As it turns out, the Mac Tools AD850 and AD800 were made by Viking Tools; in the Viking line it's model V343/V344 (1/2") or V341/V342 (3/8) with the difference in part numbers being keyed or keyless chucks. All these Viking models are discontinued, and no chuck screws available.

The lady at Viking Customer Service eventually told me that the screws were supplied to them by "Dinosaur Inc." which seems an unlikely name for a hardware vendor.

Anyone have information on "Dinosaur Inc"? I don't see anything related to hardware in my web searches.

Anyone have a source for reverse-thread machine screws?
 
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APEowner

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McMaster-Carr carries some left hand thread flat head screws. You'll obviously need to know the size in order to tell if they have what you need
 

KenC

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I would take the drill to a factory service center for Stanley-black&decker. They do dewalt, porter cable and others. They all use a LH screw in their reversible drills. Try the ones they'll have in stock. Odds are one of them will fit.
 
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Schurkey

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Thanks for the McMaster-Carr suggestion.

if by chance it's 1/4-20 LH, dewalt uses them in their drills
I think it's likely that some other drill manufacturer uses a similar screw. I need to get off my *** and determine the thread size and pitch.

I would take the drill to a factory service center for Stanley-black&decker. They do dewalt, porter cable and others. They all use a LH screw in their reversible drills. Try the ones they'll have in stock. Odds are one of them will fit.
Nearest "factory service center" is 450 miles from me. I tried a local tool-repair company, and they couldn't fathom how their brand of repair parts could possibly fit my brand of tool.
 
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Schurkey

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Update:

Finally pulled the "good" screw out of my Mac AD800A (3/8, reversible) so that I could measure the silly thing, and then installed it in the AD850A (1/2") where I actually need it more.

10-32, flat head (1/8" Allen socket) and one inch long. Reverse "Left hand" thread, of course. And, of course, NOT stainless steel (too weak.)

Eventually, I wound up at Power Tool Repair Ohio ( www.ptrohio.com ) where they list no chuck screw for the 1/2" AD850A, but the exact same screw is used on the AD800A. The screw listed for the '800 is their part number SLP5003. They source it from St. Louis Pneumatic (SLP).

I bought three, $25 including shipping, but I haven't gotten them yet. Assuming that the screw is actually correct, it will be wonderful to get the ol' girl back in proper condition. A damn fine drill--a few Viking-branded units are still available for sale even though Viking has quit making them.
 

rlitman

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Oct 18, 2010
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Long Island
My local Ace Hardware has left handed screws and bolts in the bins. But I'm not sure if they've got that specific one.
 
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