Help a new guy with table saw motor questions?

[Matthew Williams]

Hi, I just joined up and have a few questions. I'm refurbishing a Delta 34-410 contractor's saw and I'm having a few issues with the motor right now. It sounded a little rough when spun by hand so I took it apart. It looks like the bearings could use replacing, but that's not the only problem. It makes a strange hissing noise while slowing down, but only when it's almost stopped. I'm guessing that's some sort of starter reengaging? Also, the pulley and fan both have a bit of run-out and it looks like it's partly because they aren't true and partly because the set screws are off center, so tightening them down tilts them to one side. Is this amount of wobble and vibration normal on this type of saw? I figure about 1/16" but I'll get a better reading tomorrow. The pulley's have both been replaced with cast iron browning units so I was surprised to see this much wobble, although I don't see how it's avoidable with a single set screw. I might have a shop inspect it tomorrow to get another opinion, but I'm interested in what you guys have to say since you folks have so much experience with this sort of thing.


A little background for those who are interested:

I started picking up a few tools on CL since I'm interested in building speaker boxes and other not-so-fine woodworking projects. The table saw repair has turned into a fun hobby in itself and I've already fixed and tuned up a Delta 34-670. Now that the 670 is ready to find a new home, I want to get started on the 34-410. The little guy turned out to be a great bench top saw btw, but the smaller size, loud universal motor and difficult-to-use fence has me eager to get the contractor's saw up and running.

Thanks,
Matt

[Rod Sheridan]

Hi Matt, the hissing sound when coasting is the centrifugal switch bobbin rubbing on the starting switch, it's completely normal.

The fan runout isn't an issue, the pulley runout is. Are you sure the shaft and pulley bores are identical?

Regards, Rod.

[Jerry Bruette]

Hi Matt welcome to the Creek, you've come to the right place for info.

Are you seeing the pulley runout on the outside surface of the pulley or the groove in the pulley? I wouldn't be too concerned about the outside edges, but if the groove is wobbling that's an issue.

BTW most pulleys have only one set screw and it's usually right on the key. Sometimes we'll put another setscrew 90 degrees off of the one on the key, but that's not to center anything. It's insurance incase the first one should vibrate loose.

Jerry

[Alan Muller]

You shouldn't have too much clearance between the pulley and shaft unless one or the other are worn, or the sizes don't match. Usually the motor shaft will be 5/8" but 1/2 is seen and 3/4 is possible on an old or large frame motor. Take the pulley off: Is the shaft under it chewed up or noticeably smaller in dia than other parts of the shaft? If so, shift the motor or the arbor pulley so you can seat the pulley on an undamaged part of the shaft. In my experience this is uncommon because most small tools uses aluminum or zinc alloy pulleys and these are much softer than the shaft. As for the pulley, if somebody took the trouble to install steel or iron Browning pulleys, one would not expect they to be left loose enough to wear. Maybe check the clearance with feeler gauges and report back....? Seat the setscrew on the key so as not to chew up the shaft.

Alan

[Matthew Williams]

Thanks for the great responses!


Rod: good to know, that sound was the main worry for me. The pulley and shaft are both sized at 5/8" with maybe a few thousandths of clearance.

Jerry: the wobble is on the outside edge mostly. When I checked the inside edge the dial indicator showed less than .009" of runout. It did show less without the set screw installed, so I know it's making a difference, but I'm not sure if that much will matter.

Alan: There may be some wear on the pulley and maybe a tiny bit on the shaft. The main reason is most likely that it was run without the key for some time. When I first bought the saw it was missing and that caused a HORRIBLE noise. I quickly fixed that problem with a new key. I think the cast iron pulley is more worn than the hardened steel motor shaft and my calipers confirm that, although it was hard to get an accurate reading. The set screw is definitely seated on the key.

The good news: arbor runout is less than .001" the same with the motor shaft!

I'll definitely change the motor bearings since I have it apart. I was quoted around $20 for 2 SKF bearings at a local place. Going with the sealed type (6203 2RSJEM is the SKF part number for reference) like the gentleman I spoke to as well as others have suggested. Now the only question is whether or not I need to replace the pulley?

[Bruce Wrenn]

Thanks for the great responses!



I'll definitely change the motor bearings since I have it apart. I was quoted around $20 for 2 SKF bearings at a local place. Going with the sealed type (6203 2RSJEM is the SKF part number for reference) like the gentleman I spoke to as well as others have suggested. Now the only question is whether or not I need to replace the pulley?6203's are the most common bearing in use anywhere. On line, you can get them for less than $3 each. Yes they are most likely made in China. The ones in Delta saws are made in China. Order four, as your arbor uses same bearings. Unisaws use the same bearings on their arbors also.

[Jerry Bruette]

I don't think .009 runout would warrant the cost of a new pulley. Put a link belt on it and you probably won't notice a thing. Wise choice doing the bearings while it's apart, and the SKF's are industry standard. Just be sure to install them properly.

A drop of blue Loctite on the setscrew during reassembly will assure that it won't back out.

Jerry

[Matthew Williams]

The ones on the saw now were made in Italy by SKF so I figured I'll just get the same ones. If they lasted this long, they should last another 20 years. I really don't want to do this job again and I should have a nice cabinet saw by the next time they go out. I'll definitely get a couple more for the arbor too. I'll try the pulley I have now before I replace it.

Thanks again everyone, I'll give you all an update once it's done. I might even add some pics if I get the chance!