Dewalt 788 UPDATE

[Grumpy Old Bear]

I am happy to announce that the fuse was replaced and the saw does work, I was able to reattach the blow tube, which is better now than when the saw was new. The speed is still kinda wacky, so I had my wife pick up a replacement 'pot' for me. My local Radio Shack is going out of business and they didn't have the part I needed but they recommended another local store that did have the correct part, sort of. The original part fits in a 5/16 inch hole. The replacement part needs a 3/8 inch hole, and is quite a bit bigger, physically. It is a 50K ohm Linear Taper pot, so electrically it should work. It appears the shaft is a bit larger also.

I am wondering if I should go ahead and modify the saw to use the new 'pot', or keep checking to see if I can find the proper part. Any thoughts and/or concerns would be greatly appreciated.

BTW, even though I am 55 years old, I can't talk about a pot without chuckling like an 8th grader

[ike]

The question is will the part you are modifying the saw for wil always be  available.

IKE

[CharleyL]

I bought the first part to fix a DeWalt 788 from Radio Shack. It was the correct 10 K (not 50 k) ohm value and a linear taper, but the shaft was about 3" long and round. I hack sawed it to length and filed the flat in it so it would fit the DeWalt knob (check position of flat in old part with the shaft set to zero and do the same on new part or number marks on knob will be off) . That was over a year ago, and as far as I know it's still running fine. The saw is in our club's outreach program trailer and the part was given to the present leader of the outreach program to be installed. I didn't do the installation. The saw had broken loose in transit and the shaft and knob were broken off when it fell over. 

Charley

[Scrappile]

Is it possible to wire that "pot" in temporarily without modifying the hole to make certain that is the problem?  if works I would enlarge the hole and go.  If you have to replace it and can only find a 5/16 shaft later, washers would probable work to fasten it in, or it may fasten in a 3/8 hole anyway.

[Grumpy Old Bear]

1 hour ago, CharleyL said:

It was the correct 10 K (not 50 k) ohm value and a linear taper,

OI am so glad I posted this question before I did any modifying. I had my wife get the wrong size pot; I have no idea where I got 50K. Guess I don't do any cutting this weekend. Thanks again Charley. Hopefully the 10K is the proper size. I'll give my wife the old part to take along to make sure.

Everybody have a safe and fun holiday weekend.

[CharleyL]

You can take your saw apart and look at the stamping in the side of the part to verify the electrical value, or measure the resistance between the two end terminals of the part when it is disconnected from the saw with an ohm meter (multimeter).. It was 2 years ago that I did this, so checking the value of the part is likely a good idea. My brain isn't what it used to be. The part will show the value, as well as the manufacturer's part number, etc. stamped on the side of it. The electrical value and the physical shape and size are the most important parameters. The length of the shaft and the need for a flat on the side of the shaft to fit the hole in the knob is also important, but you can use a hack saw and a file to fix that. Neither is critical, so visibly the same is good enough. The part that I got from Radio Shack ad a 4" long round shaft, and worked fine after I modified it. You just need to turn the shaft of the new part as well as the original part fully counter clockwise to see where the flat needs to be and then file the flat on the shaft of the new part to match the same position of the flat on the original part. If you don't get it right, the part will still work, but the number scale on the knob versus the speed of the saw will be different, but it will still work. There is a tiny connector in the wires, so you can unplug the original part to take it to the work bench to do the soldering and to compare with the new part for where to file the flat on the shaft.. Also, file the flat on the shaft before you cut the shaft to length. The extra shaft length will allow you to clamp it in your vise to do the filing. Don't try to clamp the body of the part in the vise. You will destroy it. Clamp the excess part of the shaft in the vise instead, and then cut it to length after you have filed the flat.

Charley

[amazingkevin]

On 5/26/2017 at 7:52 AM, Stupid Donkey said:

I am happy to announce that the fuse was replaced and the saw does work, I was able to reattach the blow tube, which is better now than when the saw was new. The speed is still kinda wacky, so I had my wife pick up a replacement 'pot' for me. My local Radio Shack is going out of business and they didn't have the part I needed but they recommended another local store that did have the correct part, sort of. The original part fits in a 5/16 inch hole. The replacement part needs a 3/8 inch hole, and is quite a bit bigger, physically. It is a 50K ohm Linear Taper pot, so electrically it should work. It appears the shaft is a bit larger also.

I am wondering if I should go ahead and modify the saw to use the new 'pot', or keep checking to see if I can find the proper part. Any thoughts and/or concerns would be greatly appreciated.

BTW, even though I am 55 years old, I can't talk about a pot without chuckling like an 8th grader

Details details ,just fix it and use it it's not a collectors item.

[CharleyL]

So when are you going to fix your collection of Dewalt saws, Kevin?

 

Charley