Porter Cable plunge router motor lock - Router Forums
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post #1 of 4 (permalink) Old 01-13-2015, 10:00 AM Thread Starter
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Default Porter Cable plunge router motor lock

After the failure of my second Craftsman router a couple of years ago, I picked up a used Porter Cable 690. Several times I've needed a plunge base so I recently picked up a 6931 base in need of repair for a good price. A new plunge clamp knob, depth gauge rod and depth pointer come to about $7 plus shipping, using a 3/8" rod from my miscellany box.

The other problem is the motor lock allen bolt and associated hardware are missing. Replacements are about $10, mainly due to the specially machined clamp and nut. After studying the parts diagram and the user's manual, I get the impression this is a pretty mickey mouse way of securing the motor to the base. The clamp, nut and bolt have to be removed with a hammer tap to remove the motor, making them subject to wear, loss and pricey replacement.

Given the motor's tight fit in the base, I think a chunk of rubber compressed by an allen bolt and a small plate on the bottom should be enough to lock the motor in place. I can't see the thin metal clamp providing significantly more force. The rubber should retract enough when loosened to allow motor removal without dismantling the clamp assembly.

I'm wondering what experiences others have had with this lock mechanism. Is it as troublesome as I suspect it to be and if so has anyone found an alternative? Is my plan viable or should I bite the bullet and spend the $10 upfront and maybe another $10 in the future?
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post #2 of 4 (permalink) Old 01-13-2015, 06:50 PM
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George I can't give you any advice on your inquiry but I'm sure someone will be along to offer advice.

Rockhampton, Queensland, Australia

Enjoy the knowledge of others that can be found within.

‘Members are requested to add a first name in their profile as we are a very friendly bunch here'.
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post #3 of 4 (permalink) Old 01-14-2015, 08:43 AM
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I own a similar set-up and have never felt good about the "Mickey Mouse" clamp either. I see no reason your idea should not work but the rubber needs to get a good grip on the motor as it is purely a slip fit in the plunge base barrel. What is your source for a hard enough rubber that still has sufficient compression?
Let us know if you do this and how it works.
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post #4 of 4 (permalink) Old 01-14-2015, 09:48 AM Thread Starter
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When I lived in Rochester NY, there was a company called Chamberlin Rubber that I would visit for solutions to requirements such as this. Alas, down here in the Commonwealth I have no such resource so I'll have to wing it!

I have four possibilities:

- rubber stopper (my wife is a science teacher )
- neoprene fuel line (the hollow center would squish nicely)
- paper feed roller from a laser or ink jet printer (I have several waiting for recycling)
- bicycle brake caliper (already curved)

I've used the principal before to secure 1/4" eye bolts in aluminum tubing with a stopper, two nuts and two washers. Once the outer nut was tightened, it was nearly impossible to pull the eye out! I would shape a piece of plate stock for a clearance fit in the router lock recess so it can't spin then tap a hole in the middle for the bolt. A matching hole in the rubber would complete the assembly.
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