Did I fry my Bosch colt?

[Günter VögelBerg]

I was using my Bosch colt to route aluminum, which was probably not one of my better decisions. I was taking very light passes, using lubricant, and turning it off for a minute between each pass. It did not seem exceptionally hot. However, in the middle of a pass it suddenly lost most of its power and started making a quiet whirring noise instead of the screech it usually made. I took out the brushes and see no obvious signs of damage. I have not opened it up. Thoughts on what I should be looking for?

If it is not an easy fix I'll just buy a new one, but I figured I'd give it a shot first.

[Paul F Franklin]

First, make sure you didn't bump the speed control. Do the brushes have enough length left so they are making good contact with the commutator? If not that, my guess is that you fried the speed control.

[Bruce Wrenn]

I was using my Bosch colt to route aluminum, which was probably not one of my better decisions. I was taking very light passes, using lubricant, and turning it off for a minute between each pass. It did not seem exceptionally hot. However, in the middle of a pass it suddenly lost most of its power and started making a quiet whirring noise instead of the screech it usually made. I took out the brushes and see no obvious signs of damage. I have not opened it up. Thoughts on what I should be looking for?

If it is not an easy fix I'll just buy a new one, but I figured I'd give it a shot first.I would have left it running between passes, as the cooling fan would be going, plus it would be under no load. The speed control would be my first suspect if there was no "magic smoke."

[Günter VögelBerg]

I would have left it running between passes, as the cooling fan would be going, plus it would be under no load. The speed control would be my first suspect if there was no "magic smoke."


I plugged it back in and when I adjust the speed control to the highest setting it brienfly reaches what sounds like full speed then flutters a big and goes back to low speed. Should I get the multimeter out and start testing things or just order a speed control? I can get them for $22.

I also see that Bosch now has a 7 amp colt, so I am wondering if I should just buy that. I've had this router for at least ten years. I don't think it owes me much.

[Jamie Buxton]

I plugged it back in and when I adjust the speed control to the highest setting it brienfly reaches what sounds like full speed then flutters a big and goes back to low speed. Should I get the multimeter out and start testing things or just order a speed control? I can get them for $22.

I also see that Bosch now has a 7 amp colt, so I am wondering if I should just buy that. I've had this router for at least ten years. I don't think it owes me much.

I had a DeWalt router which developed symptoms like that. It turned out that the armature had a wheel on the end away from the collet. The wheel had magnetic poles on it which were observed by a stationary sensor. The signal from the sensor told the control electronics how fast the armature was turning. On my router, the wheel loosened up, and would spin pretty easily on the armature. A spot of super glue fixed the problem. Maybe there's something like that happening in your router.

[Mark Daily]

How good a job did it do on the aluminum? How did the bit hold up?

[Günter VögelBerg]

How good a job did it do on the aluminum? How did the bit hold up?

It did a terrible job on the aluminum. I ended up scrapping the work piece. The cut was rough. I was using a straight two-flute carbide bit. The bit actually held up well. I suspect a spiral but would have given better results, but I did not have one with a bearing.

[Paul F Franklin]

I was using a pattern bit (top bearing) to route a recess for some T-track. I was using a bora edge clamp as the "template". Evidently the flush trim bit was a tad larger than the bearing because I got very fine aluminum flakes shaved off the clamp. Had to be less than a thousandth shavings, but in that case it left a very smooth finish.

Regarding whether to try replacing the speed controller or just buy a new router: $22 and some time and aggravation will get you some unknown probability of fixing a 9 year old 1 HP colt. $110 will get you a new 1.25 HP colt. If I wasn't in a hurry for it, I'd probably go for replacing the speed control. Worst case you get a 1.25 colt for $132.

[John Terefenko]

Have about 5 of those routers and love them If doing aluminum use the bits that are used on CNC machines. Now the name slips my brain Someone will post them. That is a tough call but they go on sale many times during the year. I use to get them in Home Depot at their Christmas sales. But have seen other place have them too.

[Charles Grauer]

It could be the bearing in your router that has gone bad?

[Günter VögelBerg]

I was using a pattern bit (top bearing) to route a recess for some T-track. I was using a bora edge clamp as the "template". Evidently the flush trim bit was a tad larger than the bearing because I got very fine aluminum flakes shaved off the clamp. Had to be less than a thousandth shavings, but in that case it left a very smooth finish.

Regarding whether to try replacing the speed controller or just buy a new router: $22 and some time and aggravation will get you some unknown probability of fixing a 9 year old 1 HP colt. $110 will get you a new 1.25 HP colt. If I wasn't in a hurry for it, I'd probably go for replacing the speed control. Worst case you get a 1.25 colt for $132.

That was my rationale. I ordered the part. I have a back injury right now and cannot do the larger projects I want to be doing, so fixing the router will give me something fun to do with no exertion.

[Jim Becker]

A lot of folks use O-flute spiral on aluminum on CNC. And yea, you gotta take little bites unless you have a big-honkin' machine. A hand-held needs to eat really small by that measure.

[johnny means]

Personally, I wouldn't put a dime or a minute into repairing a Bosch Colt. If you wear one out, it's very unlikely to have a single problem. Some other issue would be waiting in the wings.

[Mark Daily]

It did a terrible job on the aluminum. I ended up scrapping the work piece. The cut was rough. I was using a straight two-flute carbide bit. The bit actually held up well. I suspect a spiral but would have given better results, but I did not have one with a bearing.

Interesting- guess I won’t try that...:)

[Jim Dwight]

You've already ordered the part but when my speed controlled PC690 went on the fritz, I bypassed the speed control and now have a 1 speed 690 (actually a second one, the other never had speed control). I have a separate speed control I can use if I need it. I almost never change the speed of my routers (Colt included).