Join Date: Aug 2015
Location: Regina, Saskatchewan
Hello Bruce. Two years has passed between your post and my reply, and it seems you are not active on this forum anymore, so I'll just post this for the benefit of someone else who might need information.
I am also having belt issues with my Delta 34-670 'contractor' saw, and I posted on another woodworking forum and got nothing but crickets in response as well. It seems like you and I are the only people in the world with Delta 34-670 saws. Apparently not many woodworkers know about these saws with internal belts. I've seen a few posts on other forums where a woodworker requests advice, something like this: "my blade isn't turning but the motor is running...what is wrong?". I know immediately what is wrong, but you can tell from the other replies that few people know about the internal belt saws.
I've had my saw for over 20 years, and I've had an ongoing problem of poor belt life. As you mentioned, this model of saw has an "internal belt". It is a small toothed belt about 1 1/2 inches wide and 3 inches in diameter. It is hidden behind the black plastic cover on the end of the motor. My saw keeps stripping the teeth off the belt. I've gone through numerous belts over the years. The most recent failure: I had a belt last only 16 days! You can tell when it starts failing when you hear a little chirp when you hit the start switch. That's the first few teeth being stripped off. It will quickly go downhill from there - you'll notice a loss of cutting power, and then it won't cut at all.
The belts are not cheap and are not easy to change, considering how often they need to be changed. I've taken to buying several at a time so I always have a spare. You'll see them on eBay for a seemingly cheap price, but by the time you pay the shipping, it adds up. I recently bought two on eBay from a company in New Jersey. I hope they will be better quality than the ones I've previously bought. I think they were about ten bucks each, but with the shipping charge, it came out to about $30 each.
I suggest you download the owners manual from the Delta website. It details how to change the belt, although they make is sound far easier than it is. You have to turn the saw over, position the blade in a certain way and remove a cover, and a belt retainer. Then they say "...and SLIDE the belt on." LOL! In reality the belt is so tight that you have to work it on a millimeter at a time while turning and turning the pulleys. I have my saw mounted on a custom stand, so I can't turn it over. I have do all this standing on my head under the saw.
My personal theory about the belt issue is that the belt is under-designed for the saw and fails because of over-stress when you start the saw. As you know, this model of saw is quite powerful and starts almost instantly. It goes from zero to full speed in about one second. Spinning a ten inch piece of steel, this must put an incredible amount of stress on the belt teeth...and just strips them off.
Advice for someone buying a table saw...avoid the internal belt models. When I bought it the salesman sold me on the idea that having an internal belt, without a motor and V-belt hanging off the back, made the saw more compact for the weekend warrior's workshop. If I bought another saw I'd go for the conventional motor and V-belt.
I wonder if there isn't some kind of electrical hack that could be done to slow down the startup of the motor and lessen the stress on the belt. But I'm not an electrical guy.
Last edited by slowpoke; 08-30-2015 at 02:51 PM.