my new radial arm saw

Well it seems I jumped the gun a little. The bearings don't seem to be perfect. probably because I discovered the blade is warped some but the bearings were not the problem. All these posts may help some one in the future I hope. here is what I discovered.

I kept reading things about 3 phase motors and converters until something I read made me remember something about one of my volt measurements. one of the outputs to ground was over 200v while the other two across ground were 125v. That made me realize the placement of that leg must be crucial. t3 was the highest leg across ground. I moved it to l3 on the motor. that made the saw spin smooth but backwards , so I switched L1 and L2 on the saw and that made it spin correctly. I can not believe how much I have learned.

The highest voltage leg in 3 phase must be placed properly to get smooth rotation because (I think) if that leg does not strike with power at the right moment it is actually going to fight the rotation. picture the motor trying to go through the three phases -- forward, forward, backward ---or forward, backward, forward. If the other two phases are wrong it will spin backwards but it will still rotate smoothly.

At least that is what i think I have learned. there is probably better tech. jargon to use.

I made 2 cuts with the warped blade. one in a 2x6 and the other in a 6x6 post I had. the saw didn't know the difference even with a bad blade. I could rip a 6x6 post down the center with this thing faster than my 3hp jet table saw could rip a 3/4" piece of pine.

Its kinda scary. Now I need to find a new blade.
 
OK Keith like I said in my PM it doesn't look like you let all the smoke out, now while you are in the fixing mode I would still pull the motor off the saw and replace the bearing. It is a simple bit of maintenance and very cost effective. If you need bearing puller they are very cheap at harbor freight. The bearing can be had from and bearing house and shouldn't cost more then a coupla bucks each.
 
OK;
I hope everyone isn't getting board with my stumbling through radial arm saw land. It is kinda exciting for me. especially because every time I think I have a big problem it seems to get fixed. Unfortunately a new different problem comes up each time.

Now I have discovered that the blade is not warped but the saw has some runout. I didn't think RAS did that and I hope its a fixable problem because so far I am in love with this giant. I just tried a 12" dewalt miter saw blade. it had the same arbor hole. I just did a 33" cross cut with it. It was actually a rip but I did it like it was a cross cut. It looks as though I could cut at least 2" in depth with a 12" blade, the saw starts up much much faster, I think it gives me a longer cross cut because the fence can be closer to the column and

best of all, the blade doesn't take an hour to stop spinning. the 20" blade spins for ever after you cut the power. If this thing has an internal break its broke.

Don;
Is replacing the bearings that easy in an electric motor? I have replaced crnak bearings on small engines like chainsaw but the very first one I did never ran correct again. I wouldn't want my first electric motor rebuild to go the same way.
 
Keith, Replacing the bearing is very easy in a motor if you have done it in an engine this will be a no brainer. A 3 phase motor is easier then a single phase motor. If you could take a picture of the end of the motor opposite the shaft I might be able to help ya get started.
 
Keith, Replacing the bearing is very easy in a motor if you have done it in an engine this will be a no brainer. A 3 phase motor is easier then a single phase motor. If you could take a picture of the end of the motor opposite the shaft I might be able to help ya get started.

Great. Agin I appreciate it a bunch. Do you think the bearings would have much to do with the blade run out I am experiencing?
 
Keith I went back and looked and it should be easy to replace the bearings. It looks like there are 4 allen head bolts in the end opposite the shaft. If you take these bolts out the end bell should come off with a little persuasion (you may have to tap the end of the shaft with a piece of wood, he it's wood working) . The roter will be left with one bearing in the opposite end bell and another bearing where it was int the end bell your just removed. simply pull the roter out of the other end bell and you will have the roter with two bearing on either end. Pull the bearing from the shaft, take then to a bearing store and have them match up the brearing. When it comes time to put the new ones back on we will star another thread.


BTW the beqarin g could be the cause of the run out.
 
keith, as for the braking part on your saw,, i have seen a 20" saw run and know what you mean by spinning for a long time they didnt like it either and made a brake for it.. they took a piece of brake shoe and made a lever mechanism with it to press against the blade to stop it.. worked great..
 
....It looks as though I could cut at least 2" in depth with a 12" blade, the saw starts up much much faster, I think it gives me a longer cross cut because the fence can be closer to the column and best of all, the blade doesn't take an hour to stop spinning. the 20" blade spins for ever after you cut the power. If this thing has an internal break its broke. .....

It probably starts and stops faster because of the momentum of the smaller blade. Don't look for a dynamic brake (that essentially reverses the motor force to stop rotation). As a saw cuts, it tightens the arbor nut. But if you dynamically brake a motor, the forces are the other way... to loosen the arbor nut. European saws that have dynamic braking have three holes in the saw blade, so they can't unscrew. Other saws magnetically introduce an electric current in the blade, which can lead to braking without unscrewing the arbor nut.
 
Top