I have a home built cnc router with a 2 1/2 hp Makita router. One of those ones thats suppose to be real quiet. The problem it has been devoloping is that the rpm goes up and down instead of remaining constant. Its constantly reving up /down. Has anyone had a problem like this with a router? Am i going to need to buy a new one or is there a fix?

Does it do this when cutting, or when not cutting. Variable speed routers will do this. Whenn they start to cut, the exra load slows them down and they then speed up to try to keep the speed constant. If your not making continuous cuts, but a lot of short cuts, it'll be more pronounced. It's also more common at lower rpm's.

But, it sounds like your saying it didn't always do it, and/or it's getting worse? If that's the case, maybe there is a problem with the speed control. If there is a problem, you should be able to get it repaired at an authorized Makita service center.

Thanks for your reply. It is a variable speed router. And no it didnt always do this. So far not very impressed with makita.

If you've had it for awhile, check the motor brushes for wear. A wore down brush will have less spring tension on it causing it to "float" on the motors commutator while running.

Well....just my suspicion....but I suspect that they used an optical sensor instead of a hall-effect sensor and the optics have dust on them.....of course if you had enough wobble .....the hall-effect would have similar symptoms....How old is the router....how much have you used it.....does it only occur when you're cutting certain material??

Ive only had it for 8 months and use it about 8 hour a week. I just cut wood with it. When I first start it up it will cut fine for about 10 to 15 minutes. Then it will start going crazy. DO you know if cleaning that sensor is easy or not? Im thinking it's either that the sensor is shot or that it is dirty llike you said. I dont think it's the brushes since I havent used it a whole lot.

Looking at a Makita parts diagram I don't see a sensor, just a speed controller SO the sensor should be part of this assembly. Doesn't appear to be tough to get to and check out and clean.

http://www.makita.com/assets_product/RF1101/parts_breakdowns/RF1101.pdf

8 months = 32 weeks times 8 hours a week = 128 hours

in my opinion thats not very much time

Well.....it has been a while since I've worked with router design spec.'s.....in the past a router had a normal life usage of about 20 hours and therefore the router's were designed for 120 hours of use......we are not the normal router users......bearings are a little better today....but housings are no longer metal.....bearings get hot....housing are made of glass filled plastic....

Sears and others sold home use routers and had a commercial line of routers for heavier duty use.....

You might want to check the line voltage at the outlet too. I've seen line voltages swing around enough to induce a similar effect to what you are describing in variable speed hand drills. The line conditions change from day to day and week to week as well.

Hello. Chances are it's either the electronic speed control or the brushes. If you can get to them, pull the brushes out, turn them 180 degrees and give it try. If that doesn't help and you're willing to dive in a little deeper, bypass the speed control by disconnecting it and wiring the brushes to an external speed control like the <$20 one Harbor Freight sells.

BTW, 128 hrs is good for the typical router. My 7518 Porter Cable's manual says it should be serviced every 100 hrs. IMHO, this is terrible for a $300 machine.

JR

So I see above I have a couple of opinions that a makita/ porter cable router, even the 3/14 hp supposable "industrial" routers are going to start having major problems at around 120 hours? Thats simply pathetic to put it plainly. I have a dremel tool that I beat the crap out of. It has 100's of hours on it and is still going strong. I would think a heavy supposable "industrial" router would give 100's of hours of use with out major parts going bad...... Any way about that speed control would it maintain constant rpm ,more or less, under load? Im not sure But I think how the speed controls in the makita router work is that applies more current under load to maintain the rpm. Would a harbor freight special do that? I'm pretty sure at this point that its the speed control unit thats going bad . I took the brushes out and they look fine, lots of brush left.

...... Any way about that speed control would it maintain constant rpm ,more or less, under load? Im not sure But I think how the speed controls in the makita router work is that applies more current under load to maintain the rpm. Would a harbor freight special do that? I'm pretty sure at this point that its the speed control unit thats going bad . I took the brushes out and they look fine, lots of brush left.

Don't waste your money on the HF "speed control". I have one and it's useless. All it is is a glorified light dimmer.

Proper speed control is done with a feedback circuit. When the speed slows it applies more torque (current) to get the speed back up.

I, also, think the problem is in the speed control circuit(s?). If it were my router I would do one of two things:

1. If I could live without VS, I would bypass the circuits and hard wire for full speed.

2. If I really needed the VS I would replace the circuits.

You will probably find that the ring magnet that is sandwiched between the comm end bearing and the commutator has come loose on the shaft, or the magnet itself has cracked within its plastic moulded holder (normally the red band below the bearing with Makitas). This means that the sensor coil withing the electronic section is getting the wrong information, so it cannot tell what speed the motor is actually running at.

If the magnet isn't obviously broken, pull the comm end bearing off and resecure the magnet with a drop or two of anaerobic adhesive, such as Loctite studlock. This is also a common problem with many of the Dewalt (Elu) routers and the big Freud. The manufacturer's difficulty is in moulding a hole through the magnet material that is tight enough to grip the shaft without putting so much stress on the brittle material that it cracks. Use only a very small amount of Loctite and wipe off any surplus, else you run the risk of an electrical short between the commutator and the shaft. Preferably get a qualified tool engineer to flash test (Hi-pot) the tool for electrical safety after you have done this.

This is a defect in some earlier Makita routers and was repaired on both of mine free of charge, even after the warranty had expired.