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Black & Decker High Speed Rotary Dremel Tool Mod

Picture of Black & Decker High Speed Rotary Dremel Tool Mod
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Black and Decker gets a bad rep sometimes, but they really do have a good design/engineering dept that occasionally puts out a product that stands out from the crowd. I still love my Black and Decker 2 temp soldering iron/station which is only beat by actual professional soldering stations but at $20 can't be beat. This instructable, however is in regard to Black and Decker's foray into the rotary/dremel tool market.

When their RTX tool first came out it was an infinitely variable speed tool with markings from 1 to 6. The new ones are marked as only 3 speed. I had one of the original models. I actually got an awesome kit on clearance at walmart for only $25 which came with tons of bits, the snake extension, and a hard case with bit storage in the top which works great. This is actually one of the only tool cases I have kept and used to keep the tool in because it stores the tool and its accessories soo well. This was purchased shortly after the RTX came out over 10 years ago.

I used my RTX harder than most, constantly exposing it to wet, dusty, dirty conditions. I used it at least 2 times a week much of the time for heavy duty tasks like cutting and grinding metal. The metal filings building up on the magnets in the motor and probably some gravel that got into it while dragging it around under a vehicle is what finally killed mine. I seriously put it through more hell than most will ever put a rotary tool through. I of course took it apart and indeed something had lodged in between one of the brushes and the contacts and ripped one of the brushes out and it disintegrated into the motor. Motor was fried, even if brushes were replaceable it would not have been salvageable especially with all of the metal fillings built up in there from years of metal working.

I of course needed a replacement and I have used Dremel Tools complete line as well as a Craftsman rotary. The Craftsman was complete garbage and failed within a year. It had a plastic/rubber motor linkage which stripped out and failed. The Dremels are great, well built tools and you can't go wrong with them, especially the 4000. The replaceable brushes are a nice feature, but after over 10 years of hard use my one good brush was still about 1/4 so I think that is not a big deal. I actually like the weight, ergonomics, collet lock, size and weight of the RTX more than of the Dremel 4000. So I bought another RTX, which are advertised as 3 speed now. 

I ordered just the base tool from Amazon as I plan to continue using my original case. Got the tool and was pleased to see that it is exactly the same tool in every way except for the speed dial. I took it apart and all of the parts are exactly the same including the motor control board, and all circuitry. This includes the potentiometer that controls the motor speed. It is infact infinitely variable, they just used a little spring that catches on notches on the dial to lock it into the "3" speed locations. You can easily use your RTX with the dial in any position for variable speed out of the box. Or, you can do this easy mod and make it infinitely variable without those annoying locking positions. It will not hurt the tool, or its circuitry, and will give you fine motor control. I'm guessing Black and Decker gimped it out to keep from having legal trouble with Dremel because it is basically just as good or better as the variable speed dremels.

All you need to do is take the tool apart and remove the little spring that locks the dial in the 3 positions.

To complete this you will need a security torq bit set (the ones with the holes in the middle) and a medium sized philips screwdriver. I got a ratcheting screwdriver set at Home Depot that came with these bits as well as every other bit a person might want.  Pics are self explanatory. 

Note: I actually replaced the dial with only a "H" "M" & "L" markings with my original dial with the numbers 1-6 on it.  
lmdm2 months ago

I just purchased this rotary tool as a first-time user, and as much as I dislike disassembling new equipment before I even use it, this useful mod was a must-do for me -- the purposely crippled thumbwheel stops were annoying.

The instructions were clear and thorough -- It only took me about 10 minutes, and that's being very deliberate and cautious. The smooth variable-speed thumbwheel is much easier to control -- it's like giving the tool an upgrade!

cre8er (author)  lmdm2 months ago
Glad I could help!
Ramonsito1 year ago
I have the Black and decker RTX. Will the RTX work with the Dremel brand Plunge #335 plunge router guide?
I want to cut specific depth designs, is there a better tool for doing this?
cre8er (author)  Ramonsito1 year ago
I have used the dremel brand snake extension, as well as the dremel brand non-pluge routing attachment. The screw-on part is the same threading and size. I'm guessing the plunge router attachment should work also.
katala1 year ago
You're very welcome. Do you have an tips about cutting wheels? Are non-Dremel wheels just as good? Sometimes you can find "SE" brand fiberglass reinforced wheels on eBay for 100 pcs for $9 whereas with Dremel you'd only get 5 for $10. How good can the SE be?

I found clone emery cutting wheels, even the grinding stones, at Harbor Freight are just as good [ but bought by themselves in packs instead of a kit they are only $1-2 cheaper than Dremels and may not be worth it] , but the fiberglass wheels they sold fell apart where the Dremel stayed though.

Given your use, you must have good tips on which wheels are best. Thanks for tips!
cre8er (author)  katala1 year ago
I have had good results with off-brand Dremel tips of all kinds. It seems you pay a pretty penny for all things branded Dremel. I would rather get a 100 pack of cheap off-brand cutting wheels for the same price as 10 of the Dremel brand. Although I haven't tried the "SE" brand you mentioned.The one thing Dremel has going for it is the EZ replacement system for wheels which works pretty well but those are even more expensive, and I have had many of those detach at the EZ-replace hub part..

I have gotten some really cheap ($.50 each at my local swap meet) diamond cutting wheels which work really well and last a long time. They are solid metal discs with diamond powder impregnated on them.
katala cre8er1 year ago
Thanks for the tip. I got diamond ones too at Harbor Freight $5 for 5 including a Mandrel, not that I needed another, but more is better, you never know how long it lasts.

I'm afraid to use it on steel or aluminum, will it cut that too without going dull? I'm using it on plastic and ceramic right now.

The Dremel emery discs, 409 and 420, aren't that much overpriced, but the fiberglass and EZ Lock are. The 36 pack is $6, but clone pack is $4-5 and the Demel ones are a wee bit tougher, and last a little longer.

Also, clone mandrels can be slightly off center and make the drill vibrate where the Dremel ones are truer.
cre8er (author)  katala1 year ago
I did dull one using it on metal.
katala1 year ago
This is a great mod, I prefer continuously variable speed since one cannot know what speed is best for a piece of work given many types of materials one can work with.
cre8er (author)  katala1 year ago
Thanks for the feedback!
I still don't understand why they gimped the variable speed to 3 speeds.
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