Repairing a jigsaw with a stripped screw hole in the casing

[mark ahlenius]

Hi

I have a Bosch jigsaw which has a stripped screw hole in the aluminum casing (see the pix). I've not taken this portion apart before but when trying to repair the mechanism for tightening the blade, I took off the lower handle and when trying to reinstall it, one of the screw holes is stripped.

It would be very challenging to replace the metal casting (gear case) as I'd have to take apart the gears and many other parts.

Wondering if this group (or another site you might recommend) has some suggestions on how to repair this situation. I could try loctite, or perhaps epoxy, but not sure if that would from metal (screw) to metal. Also thought about epoxy too but figured I'd ask first.

Please see the pix I've attached.

thank you,

'mark

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[Peter Christensen]

A thread repair kit would do the trick. It basically involves drilling out the thread, tapping it with a bigger tap that has the same thread count as the old one and screwing in a special spring into the threaded hole. It will have the same diameter and thread pitch as the original screw. Helicoil (http://www.helicoil.in/helicoil.htm) was the originator but others make them too. You might find a guy that does automotive repairs that may have them in metric.

[Dan Friedrichs]

As Peter said, inserting a helicoil would be the "right" way to fix it.

But, could you just tap the hole to one-size-larger screw and use a larger screw?

Does the screw grip the threads at all? If so, and if this is a screw you don't anticipate removing again, I'd be inclined to smear some JB weld onto it and put it in...

[mark ahlenius]

A thread repair kit would do the trick. It basically involves drilling out the thread, tapping it with a bigger tap that has the same thread count as the old one and screwing in a special spring into the threaded hole. It will have the same diameter and thread pitch as the original screw. Helicoil (http://www.helicoil.in/helicoil.htm) was the originator but others make them too. You might find a guy that does automotive repairs that may have them in metric.

Hi Peter.

Was not familar with that approach.

My only concern is that below this hole is the gearcase and unless I took it all apart, that the filings would fall into the gears, etc. Agree that this is probably the 'right' way to solve the issue. Am just bummed that I've only had this unit for maybe 6-7 years and not used it very much. I bought it new and not sure why the threads are shot on the casing.

The jbweld idea is getting more attractive to be honest.

thanks again - to both of you.

'mark

[Ronald Blue]

What may have happened is a common occurrence when you have steel mated into aluminum. The threads came out when you removed the screw. Why only one did it is a good question. As mentioned the helicoil is an option. But they aren't a sure thing. Read the link attached. As for the chips getting into the gear case. Can you drill and tap with it turned upside down? This isn't as easy but it could keep from having the issues with getting unwanted trash in the gear case.

acmeindustrial.com/insert_comparison.html

[Dan Friedrichs]

Is the hole actually all the way through into the gearbox? If not, you can use a "bottoming" tap and you wouldn't have to worry about making the hole too deep and getting swarf in the gearbox.

[mark ahlenius]

Is the hole actually all the way through into the gearbox? If not, you can use a "bottoming" tap and you wouldn't have to worry about making the hole too deep and getting swarf in the gearbox.

yes all the way through into the gear box. I can see the grease down below.

thx

[Bobby A Thompson]

May not work, but I would try loctite if there is enough treads left. Be sure and get the blue. That one is for a screw that can be removed.

[Peter Christensen]

You do have another option and that is to find a dead one and salvage the case from it.

[Benjamin Miller]

Mark, the way automotive machinists keep chips from falling into engines is to pack the drill bit with grease before drilling. The chips then stick to the bit and can be easily extracted.

[Bill Dufour]

It is probably a metric thread so maybe you can switch to a US thread that is just a hair larger. Try to keep the thread pitch or lead the same.
Bil lD.

[mark ahlenius]

Hi

Just wanted to report that I got this one repaired. After reading about helicoil and the other alternatives, I went to my local Ace Hw store and found a aluminum insert distributed by The Hillman group and purchased the allen key and screw+coupler tool kit to install it. I drilled out the hole to 9/16" and then inserted the threaded plug into the hole with expoxy. Before I drilled out the hole I put some tape and paper towel under the hole to catch the metal shavings. I had a little problem with the install because the thickness of the Bosch aluminum casting was thicker than the insert. But with the pressure exerted and the epoxy, I think its all good now..

After inserting the insert into the hole, I had to peen over the lip a bit and walla! it worked just fine. Got it back together and the jig saw seems to be working just fine now.

thanks everyone for your recommendations!

'mark
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[mark ahlenius]

Thanks Ben, that's a great idea. I'll keep that one in my back pocket (not the grease!) for future use.

'mark