Just purchased and setup my new Unisaw. I have noticed that the saw seems to jump a bit when you first start it. Everything is tight, and there is no play between the base and floor. I was wondering if the belt tension might be too slack, allowing the motor to lift?
Any suggestions as to what might cause it to jump and make a noise at startup? It is not as bad without a blade on, but I doubt that it would pass the DIME TEST. Once it is running it purrs fine.
Cheers,
Nathan
Replies
Mine is about a year old and it was not used for the first 6 to 9 months (I had to replace a complete shop due to a fire) but when I first got it, the saw would make a HUGE BANG when first turned on. It still does this a bit now but not as bad as when i first got the saw. I like you looked at everythign and could find no cause. Only thing I could think of was the belts. I looked at replacing these with link belts but the cost of the link belt seamed high.
Let me know if anyone comes up with a fix for this as I would be interested in it also, as I still have a bang on the start, it is just not as bad as when the saw was first put into use.
Doug Meyer
I wonder if the belts might be a tad too tight ...
Possibly, if you slacken them just a scosh, it would provide a tiny bit of slack to absorb the jolt of start up and spread it out a bit.
Worth a try, no?
My Unisaw is about 20 years old, I bought it new, I like to keep my belts tight, it "jumped"
when it was new, it still does it.
This saw has been used professionally for all these years, I just got used to it.
The bearings have never been changed, the saw is still as tight as it was when new.C.
Fair enough but he seemed to be looking for a solution not acceptance.
My Unisaw always jumped at start- tried loosening/tightening/over loose and over tight.
After 6 years I finally bought link belts and it has 100% stopped.
If you search online you can find link belt for as low as 4.99 per foot. usually 6.99
My Woodcraft Mgr. said I could return it if it did not perform as I expected.
good luck
dave
Well, that's good to know that it can be remedied. I think link belts may be my last resort. I think I found the culprit. I removed the blade insert and shone a flashlight on the belts while starting it. The belts do shudder / bounce quite a bit at startup, and a bit while running. I would say this is the culprit. I decided to check the alignment between the two pulleys and found them out about 3/32", also they seemed to be 3/4 to 1" of slack in them (by squeezing them). Not sure what it should be, but will get them aligned before tightening. I think I'll remove the table and check everything, as I can't seem to tap the motor pulley further down the shaft to line it up.It seems with all the machines that I have bought, that I need to do a tuneup from the ground up to get them in optimal working condition. This Unisaw has been no exception. At least once it is aligned it should stay that way. I still can't get over the size of the motor, beefy trunnions and welded cabinet. It has made my shop. This is my first tablesaw, and is a nice upgrade from my Craftsman RAS.Nathan
Nathan, I am dazed and amazed that in 7 postings no one referenced calling the DELTA TECH SUPPORT GUYS? Just call the the parts # get the new B&D/Dewalt parts center and ask a very hard tech question about a Unisaw and they send you to (or give you the phone#) for Delta's folks in Jackson, Tn. (don't lose that phone #)
I have called them many times for parts/problems and advice on both PC and Delta and they were outstanding. I can't believe that they never encountered this problem before. Paddy
Fantastic advice ! Who should know better than the manufacturer??
Certainly sounds to me as though the belts "take a set" when the saw is idle. A few minutes running smooths out the distortion and the beast quiets down. Link belts seem like the answer - if it really bothers you..
Frosty
I had the same problem and found this to be helpful.
Can't remember where I got this advice but had it saved.
On the elevating shaft, inside the saw toward the back, there is a round stop collar with a locking set screw. First crank the blade down, and then up just a few turns, enough to tension the elevating shaft. Now check to make sure that the stop collar is seated all the way back against the rear trunnion assembly. If it is not, loosen the set screw and tap the collar toward the back of the saw, and then re-tighten. If this collar is allowed to move forward, the whole elevating shaft will move back and forth, allowing the blade arbor to jump when the saw starts. This causes the "clunk" on start up. Another source of this noise could be a loose arbor pulley. There are two set screws in the grooves of the arbor pulley. They can be accessed from underneath the saw if you rotate the arbor until they are uncovered by the drive belts. Make sure you unplug the machine before attempting this!
Good luck,
Glenn
Glen, that is a good point. I found that link yesterday and checked the saw. There is no front to back play in the elevation shaft. The vibration really seems to be in the belts, and having the pulleys not properly aligned (almost 1/8" off) and loose might be the problem. I will align and snug them up tonight. I realize that when they are properly broken in they will be more pliable and, therefore, run smoother.
I just want the saw to perform as it is intended, not neccecarily perfect with a bunch of aftermarket stuff.
Sounds like you have the usual "Unisaw Clunk". It dosent hurt anything, and it should still pass the dime test. I doubt that the saw "jumps" as much as it makes a loud sound.
I installed link belts a couple years back and there was a slight difference. Really not worth the money unless you just want peace of mind.
Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Well, I got the "unisaw startup jolt" pretty much fixed last night. At first I tried tightening the belts, but that just made the startup that much more abrupt and jolting. Much to my suprise when I loosened the tension (a fair bit) the jolt went away. It now passes the nickel test every time(couldn't get my dime to stand upright). I pulled the blade insert and shone a light down on the belts. Before the three jumped around quite a bit during startup, but now they rise in unison and level out. Very happy that this was a simple fix.
I did notice that there seems to be a bit of play between the raise and tilt gears. I can push the motor back and forth, as well as up and down and see play between the gears and triunions. Oh well, not sure if this is by design or poor machining. Regardless, it works very well and I am pleased with my purchase.
The motor hangs on a pivot so you can move it around, especially up and down. It is the arbor that should be rock solid.
I can confirm your observations about the belt tension. I really dont understand why they find it necessarry to use three belts. I have seen larger (12") and more powerfull saws that use one belt. There are also a lot of moulders and planers that use one belt even though they have 5 horse motors. I guess it is a throw back to the days of "under engineer and over build". I have considered running one belt, that would signifigantly reduce the belt drag. But I haven't needed more power so.... Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Too bad manufacturers don't use motors with a " soft start" feature, or is this just a Delta thing?
Paul
Soft start on a large induction motor would probably cost $100+ for the electronics.
John White, Shop Manager, Fine Woodworking Magazine
Delta was touting the use of three belts when they first came out with the Unisaw, including the smoothness. Even back then they recommended running the belts loose. I run mine sloppy-loose, and after ten years, they still look like new. Running them loose removes them as a source of vibration, for the most part, and also as a direct transmission path for vibration between components, especially when under light or no load.
One belt (an AX belt, anyway, which didn't exist in 1939) certainly could handle a 5 hp load at that speed with those size sheaves, but I think Delta is kind of locked into what they have now. PM went to a pair of 3VX belts for the 66, which are narrower but with higher power handling capacity (for the same speeds and sheave sizes) than 4L, A, or AX belts, but I don't think they were as heavily invested in the design since it's considerably younger the the Unisaw.
Edit: Back in the late thirties, I believe v-belts were still natural rubber and cotton, and had relatively low power handling capacity (based also on longevity), so multibelt drives were common even on small machines with low hp. The original Unisaw also ran at about 3150 rpm, so higher belt loads were required to transmit the same power as running the arbor at 4000 rpm.
Be seeing you...
Edited 1/31/2007 12:39 pm ET by TKanzler
That is great information. Thanks.Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
"Edit: Back in the late thirties, I believe v-belts were still natural rubber and cotton, and had relatively low power handling capacity (based also on longevity), so multibelt drives were common even on small machines with low hp. The original Unisaw also ran at about 3150 rpm, so higher belt loads were required to transmit the same power as running the arbor at 4000 rpm."
Thats right about the time my Unisaw was made 1940 but I have a newer motor.Good, better, best never let it rest until your good is better & your better best.
You're welcome.
There is a lot of mass with a lot of energy being applied to it. Without damping, its sort of like hitting a brick wall.
:) Yeah, thanks. It was a good suggestion, and the right answer.
I'm a late entry into this topic, but having just set up my new 3 HP Unisaw I'd like to throw my 2 cents in. Like the others who have posted, my Unisaw starts with a jump, not quite a bang, but once my zero clearance insert popped out. I thought the belts were not tensioned enough, but tightening did not change the jump. I called Delta support and was told that the jump was normal, just a high torque motor going to full power in less than a second. I called two Delta approved service centers for second opinions, and they agreed with the diagnosis. Just indicated the start capacitors are sending full voltage on start up. One technician told me I could loosen the belts quite a bit, which would diminish the jump, but the blade might slip if I cut thick hardwoods; no harm, just be aware. I loosened the belts, and the jump is diminished.
I plan on purchasing a set of Fenner Power Twist link belts to replace the factory belts, and here is the reason. When I removed the belts to inspect them, they (although brand new) were clearly oval, not round. I re-installed them all in the same position and when I hand turned the blade 90 - 120 degrees from rest, the blade spun back to the resting position, sometimes backwards. It seemed to me the oval belts were returning to their resting position (i.e., where the oval ends were each on a pulley - either the arbor or the motor). I removed the belts, and using a silver sharpe, made a dot on the oval ends of each belt. Then I reinstalled them so that the dots (two per belt) were equally spaced (approximately 60 degrees) apart. When I then manually turned the blade, it rarely moved to a resting position, I presume - since the oval portions of the belts were equally spaced. While this had nothing to do with the jump at start up, I discovered, the strong vibration at shut down was now virtually eliminated. Whether these belts had taken a set from the brief time the saw was manufactured to the time I purchased it, I don't know. Regardless, I don't think they are a matched set as some have said, nor do I think they are of any special manufacture not to be replaced with non-factory belts (as others have posted). I have used several other cabinet saws which have started up smoothly, without a jump. I'm otherwise satisfied with the Unisaw, but will install the link belts and hope for smoother starts and shut downs.
Hi Fred,Glad to hear from someone else with similar experiences. I also rotated the belts so they didn't have the same set, and loosened them. My saw's startup and shutdown is now very much smoothed out. I have found that some of the startup vibration noise is coming from the factory blade insert. I used electrical tape to take out any side-to-side slack. Will be making a zero clearance insert sometime soon.I have noticed that the outer arbor washer is very poor quality. It appears to be stamped steel and is not even close to being flat. Also the factory insert is severely twisted, probably 1/8" height difference - making it impossible to level with the table. I also find that the milling of the extension wing is quite rough. I haven't called Delta regarding replacement of the washer and insert, but doubt that I would actually get a replacement. Do you think it's worth giving them a call?All that said, I am still quite pleased with my purchase, especially considering the discount that was offered.Nathan
Hello Nathan,
I would definately call Delta support. My extension table had a slight (1/16") dip in the center where it bolts to the iron wing, which besides being a defect, albeit slight, caused a problem with the Unifence support pad. I called the Delta support, and they said they would ship me a replacement. All they asked was to fax them my sales receipt. I haven't received it yet, but, yes, I'd call them for a new arbor washer and table insert. My arbor washer was flat, but I installed a set of Freud machined arbor washers, a lot more mass and flat. As for the machining on the table being rough, mine is the same. I was a bit surprised, but it is flat, so I waxed it up and I'm OK with it. I was hoping it would have that "mirror" finish, but I guess we could get the abrasive pads out and try to buff it out, maybe some day. All in all, like you, I'm happy with the Unisaw. Which fence did you get? I splurged and bought a Jessem Mast-R-Slide. Wow, what a difference being able to cross cut up to 36"! It's not cheap, $475, but if you've ever been frustrated by the stock 12" cross cut capacity of your Unisaw, this is for you. Great product. I'll post when I get the link belts installed. Cheers!
Fred
Nice add-on. I'm still trying to decide how to build a decent crosscutting sled. My saw came with the 30" Unifence, including the tableboard and legs. It was on clearance on Amazon for $1140, everything in. I like the fact that the fence face is 43" long. Took a bit to get it adjusted to glide on the table. Definitely a quality fence. Might have preferred to have the Beismeyer, but as this is my first saw - I'll have to wait and see.Nathan
You can also purchase belts that have small notches all around the inside of them & they seem to be more pliable. This is what I have on my saw & I don't think they will cost as much as the Fenner belts. I have no clunk on start up. Of course it could be old heavy 1940 iron.... Ha Ha Ha ...Good, better, best never let it rest until your good is better & your better best.
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