Blade will not go up!

[Skip C]

I am in the middle of building 2 jewelry boxes and I tried to raise the blade today and something seemed to let go in the elevation mechanism and the blade will not go up -- but it will go down.

I checked under the saw and the horizontal and the vertical bevel gears do turn.

So what do I have to fix? I can't see what is wrong but I hope I don't have to do the dreaded helicoil replacement drill!

Regardless of the fix needed, what is the best method to get at the problem? should I just unbolt the saw from the stand and turn it upside down? will that give me enough access? I have tried w/o success to remove the right side panel but I was never able to remove the receptacle from the panel -- any suggestions?

I forgot to mention that the saw is a bt 3100 and I cleaned and lubed everything about a month ago and it wasn't in bad shape before cleaned it but wanted to get ready for my new projects. Thanks in advance for any suggestions and remedies!

Skip

[frumper64]

Right panel removal

The receptacle does not come off with the right panel. It stays attached to the framework of the saw. The panel just rides behind the receptacle. Just take out the screws and the right panel will come off. It will remain attached by the ground wire which connects to the green screw you can see on the right hand panel unless you disconnect it there. I moved the ground on mine to the front panel so as to make removing the right one easier. Once you get the panel off you should have a pretty good look at whatever the problem is.

[JimD]

This is pretty unlikely to be the female threads in the motor casting and much more likely to be debris. Even though you cleaned and lubed fairly recently the BT3100 likes this a LOT. I would start with that. It has always solved this issue for me. Once I bought all the tools and the helicoils convinced I needed to do that job and then I finally looked at the mechanism and it obviously needed cleaning - which solved the problem.

Another reason I don't think you've stripped the threads is the handwheel of the BT3100 is plastic and goes over a steel shaft. When there is even a little resistance in the steel shaft, the plastic handwheel just expands over the shaft and the shaft doesn't turn. The handwheel is not capable of generating the force necessary to strip out the threads in the casting IMHO.

I hate stopping in the middle of a project to clean but that is almost always what the BT3100 wants.

Jim

[pelligrini]

Cleaning again might solve the probem.

When you said "horizontal and the vertical bevel gears do turn" did that mean that when you operate the wheel the threaded rod that goes through the casting spins and the blade does nothing? If so, looks like you'll be needing a helicoil kit.

[Stytooner]

I concur with Erik.
Either the helicoil or replace that part with a used one from a cheap saw or parts of one.

[Skip C]

Erik, yes, that is the case. If i need a helicoil, where do I purchase one. And it seems like a big job that i don't look forward to doing!

If I take it apart, what am I looking for to be broken - a stripped shaft housing on the motor?

And I am not sure why the will still go down? maybe just the weight of the blade and mechanism is enough to lower the blade?

Skip

[LCHIEN]

probably jammed with sawdust. Clean the raising (elevation) screw. Use a shopvac on the rear port when cutting in the future to help eliminate dust buildup.

Probably goes in one direction because the dust is on the other side and jammed up the threads.

[pelligrini]

A good hardware or autoparts place should have one. We used to have a kit floating around some time ago.

There's a couple really good threads on replacement, but I can't find the ones I was thinking about right now.

This one has a couple photos of what you're going to fix:

http://www.bt3central.com/showthread.php?t=52213

Found a good one in the articles Section:

http://www.bt3central.com/showthread.php?t=46863

The Old Articles section has a good writeup:

http://www.bt3central.com/index.php?page=articles

[mpc]

If you have trouble finding a Helicoil kit, try:
1: many NAPAs offer small machine shop services; they'll have the Helicoil stuff.

2: look in the yellow pages for Automotive Machine Shops. They'll sell the Helicoils and may be willing to do the install for a few bucks - might be cheaper than buying the whole kit (Helicoil + tap + insertion tool)

3: the greasy independent car repair garage probably knows where to get this type of stuff locally too. Dealer repair centers and big-chain repair places often farm machine shop work out, or just use all-new parts, rather than knowing the tricks to saving pieces so they'd not be as much help.

mpc

[Skip C]

thanks to all for the help and suggestions. I guess a helicoil is in my near future! I checked the saw again last nite and it is very clean but I think that the damage was probably done a long time ago. I had used several products to clean and lube the gears and bevels but none of them really worked very well or very long until I found a product called Move-it which is great and does not attract dust; but I guess I found it too late!

We are off this morning to Rochester, NY for my younger son's wedding this weekend so the saw will have to wait until next week.

Skip

[Skip C]

We are back from the wedding which was very nice -- my wife cried only several times! And the weather was perfect which always helps.

Yesterday I removed the motor and discovered that there are several little machine shops in our little town - pretty surprising. My first stop was at a one man shop (no sign even) where the owner was very nice but he only did high end cnc work for the aerospace industry - again, who knew? Second stop was at a auto machine shop that I had passed many times and they were very helpful and had a new helicoil installed within 3 hours! Charged $48 which I thought was reasonable given that the heli kits online ranged from $32 to $70 plus freight and now I shouldn't have to fear that the new insert is misaligned!

So today I have the adventure of putting everything back and hopefully not finding any spare parts after I think it is completed!!
Skip

[LCHIEN]

sounds like a reasonable outcome for modest money and a high confidence factor.

[JimD]

I actually bought all the pieces already when I mistakenly thought I needed to do this. I'm sure I spent at least that much. I'm not worried about doing it myself but if you can get it done for the same or even less money.....

Jim

[Skip C]

I'm happy to say that the installation went together w/o a hitch and I did not have any parts left over!

However, I am surprised (and disappointed) that the elevation doesn't work as easily as before the threads were stripped. The motor goes up and down smoothly if I use both hands which I don't think should be necessary. if I use only one hand, the motion is jerky and a bit difficult. I eye balled the threaded piece and it looks square to everything but I will do a detailed inspection later to determine if the machine shop was as accurate as I expected!

i lubed everthing last nite when I put everything together and lubed it again this morning which improved things but it is still a two handed operation. I did not change the shims but they looked fine to me but I have never seen them new so maybe they are warn but I doubt it.

Also how tite should the screws be that hold the motor to the guide? When i removed them the first time, they were so tight that I thought I might strip the head of the screw although all came out just fine. I'm afraid that if I tighten them to the degree that they were originally, the motor will not able to be raised or lowered. Should I use a little lockite to prevent the screws from vibrating out?

Again, thanks for everyone's help! For those facing the same repair, it is actually pretty easy and pretty straightforward which was not my expectation going in to this project!

Skip

[mpc]

?? The screws that hold the motor to the central aluminum bits only need to be "normal" tight. Remember, these are going into aluminum so they can strip fairly easily. And the screws that hold the central aluminum parts together should also just be normal-tight. These screws do not determine how firmly the central parts "clamp to" the vertical chassis part either; in fact with the shims removed or their adjustment set-screws backed out there should be slop/freeplay in the motor support stuff! That's really the proper way to re-assemble the central aluminum parts that moves up/down:
1: back out the set screws that adjust the shims.
2: tighten the Phillips screws that hold the central parts together to what feels reasonable to you.
3: Grab the motor body itself and wiggle it side-to-side and up-and-down. It should have some motion since the shims are loose.
4: slowly tighten the shim set screws until the slop in the motor is eliminated. Going too tight on these screws will increase shim wear and make it hard to raise/lower the blade.
5: check your blade for 90 degrees (vertical), the fence alignment to the blade, SMT, etc. All of the adjustments should be checked whenever the shims are adjusted.

Did you put any wax or other lubrication on the shim faces and on the machined aluminum portions of the chassis they slide against? Simple paste wax (furniture wax, not car wax since that'll have silicone) works well.

Another thing that leads to difficult blade raising/lowering is having the splitter plate rubbing against the back of the throat opening. There isn't a whole lot of clearance to begin with so it's easy to have the splitter rub. If it's angled at all then it may clear with the blade all the way up but drag/rub with the blade lowered.

mpc