Some tools with universal motors have a soft start feature. Dunno if one exists as an outboard unit that could be plugged in, but you can definitely buy a speed controller that plugs in.....set it to low speed to start, then ramp up to full speed for cutting.
Slow down the startup of a Delta table saw
Hi all, I have a Delta 36-600 10" table saw. It uses a notched belt ("timing belt") with matching teeth on the drive shaft so it cannot slip.
When this saw starts up it comes to full speed in about 1/2 second. The inertia of the arbor and blade puts a huge strain on the belt (and other mechanical parts) during that fast startup time. I am replacing the belt for the 3rd time in 5 years because the teeth get stripped/sheared off during startup.
Is there any way to slow down the startup of this thing? I would be perfectly OK if it took 3 seconds to come to speed... I am not sure why it was designed this way in the first place. Can a capacitor or some other (safe) electrical modification help?
Thanks for any ideas!
-Mark
When this saw starts up it comes to full speed in about 1/2 second. The inertia of the arbor and blade puts a huge strain on the belt (and other mechanical parts) during that fast startup time. I am replacing the belt for the 3rd time in 5 years because the teeth get stripped/sheared off during startup.
Is there any way to slow down the startup of this thing? I would be perfectly OK if it took 3 seconds to come to speed... I am not sure why it was designed this way in the first place. Can a capacitor or some other (safe) electrical modification help?
Thanks for any ideas!
-Mark
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the only device that comes to mind is a VFD - variable frequency drive for motors. one that will handle up to 2hp will run $250 or so. they have programmable ramp-up and ramp-down capability.
was the timing belt stock on that saw? you may consider swapping it out for a v-belt/sheave system if it is a problem.
was the timing belt stock on that saw? you may consider swapping it out for a v-belt/sheave system if it is a problem.
Can you replace the pulleys with a double V-groove pulleys like most of the rest of us have. Then you would just get a little slippage at start up.
My saw has double v groove pulleys with a 3 hp motor. It might slip some, but very little. It is up to speed in about 1/2 second. I think anything loose enough to slip drastically on start up would slip when you cut. I have never replaced the belts on my saw in 13 years.
I do not understand why any company would make a table saw with cogged tooth belt. And then want to call it a timing belt. It ain't timin nothin.
George
George
"Timing belt" is how I see it referred to in various places, I don't think Delta ever uses that term. Help people understand that it is a toothed belt. It prevents any slipping, and thus belt tension is less critical, but the start-up strain on the teeth is huge.
From more research I find that what I am looking for is a "soft start" device. The automatic ones are pricey (>$100) and mostly only work with 3-phase motors. There are some indications a simple speed control device (often used with routers, <$50) would work, but requires manually dialing up the speed. Maybe more fussiness than it is worth.
From more research I find that what I am looking for is a "soft start" device. The automatic ones are pricey (>$100) and mostly only work with 3-phase motors. There are some indications a simple speed control device (often used with routers, <$50) would work, but requires manually dialing up the speed. Maybe more fussiness than it is worth.
back up the truck...
If the belt has teeth that's one thing. If the pulleys have teeth that's another thing all together. You said the "drive" pulley has teeth, what about the arbor pulley.
I can't imagine an over engineered setup like this on a table saw where the position of the blade is critical (NOT) like and camshaft in an engine...it's just overkill.
http://www.ereplacementparts.com/drive-belt-p-112786.html?osCsid=sok7av0lcc81lcfqnn3n84chu3
This saw appears to be a direct drive, and shows no pulleys or belt in this diagram:
http://www.ereplacementparts.com/delta-36600-type-table-saw-parts-c-3275_3334_9584.html
My Craftsman Hybrid saw has a multi-groove belt, no teeth. It's very thin unlike a "V" groove belt and the pulleys have small grooves.
If the belt has teeth that's one thing. If the pulleys have teeth that's another thing all together. You said the "drive" pulley has teeth, what about the arbor pulley.
I can't imagine an over engineered setup like this on a table saw where the position of the blade is critical (NOT) like and camshaft in an engine...it's just overkill.
http://www.ereplacementparts.com/drive-belt-p-112786.html?osCsid=sok7av0lcc81lcfqnn3n84chu3
This saw appears to be a direct drive, and shows no pulleys or belt in this diagram:
http://www.ereplacementparts.com/delta-36600-type-table-saw-parts-c-3275_3334_9584.html
My Craftsman Hybrid saw has a multi-groove belt, no teeth. It's very thin unlike a "V" groove belt and the pulleys have small grooves.
THIS IS THE SAW that is being discussed. Figures 66 and 67 show the belt.
It IS a weird setup. However, with this design I would not bother with any type of soft start device.
George
It IS a weird setup. However, with this design I would not bother with any type of soft start device.
George
Porter Cable used to have the same setup on their belt sanders. For that application it worked great. Then they changed to a serpentine belt and a belt wouldn't last a year before it slipped so bad you couldn't use it. I quit buying their sanders because of the belt design change. For a table saw which has so much more power I can't see the benefit.
Id look at it this way, in 5 years, youve gone through 3 belts, lets say at $5 a pop (used this as a price), so at this point youre out $15 or so. Any device you could stick on the motor to introduce a soft-start feature would likely cost at least $100, probably more if you can even find it. With those prices, youd have to go through 20 belts to equal a soft-start in price, and at your current rate of 3 belts in 5 years, itd be 30 years before you see any price savings.
All that said, personally i cant see how itd be worth it. Id just keep a spare belt on hand. Or upgrade saws, its a wash really
All that said, personally i cant see how itd be worth it. Id just keep a spare belt on hand. Or upgrade saws, its a wash really
It's more than the cost. Nobody likes a tool they constantly have to work on. You go to the saw wanting to do some woodworking and find yourself spending a half an hour changing a belt because some idiot engineer has a better idea.Id look at it this way, in 5 years, youve gone through 3 belts, lets say at $5 a pop (used this as a price), so at this point youre out $15 or so. Any device you could stick on the motor to introduce a soft-start feature would likely cost at least $100, probably more if you can even find it. With those prices, youd have to go through 20 belts to equal a soft-start in price, and at your current rate of 3 belts in 5 years, itd be 30 years before you see any price savings.
All that said, personally i cant see how itd be worth it. Id just keep a spare belt on hand. Or upgrade saws, its a wash really
Exactly. It is not the cost of the belt, it is the reliability of the tool and its lifespan. Takes at least an hour to change the belt (turn table over, unbolt the motor, remove the cover, etc). For the price it is a good saw and has done everything I need. The term "over engineered" seems right... cannot image why it was designed this way.
Thanks for all the ideas and input. I might try one of those 20A router speed controls like http://www.amazon.com/MLCS-9410-20-Amp-Router-Control/dp/B001NIK6PC.
Thanks for all the ideas and input. I might try one of those 20A router speed controls like http://www.amazon.com/MLCS-9410-20-Amp-Router-Control/dp/B001NIK6PC.
don't...
Those speed controller are designed for a motor with brushes, like a router or skill saw, not an induction run motor.
Second, I see why they did the tooth belt design. The motor output shaft is about 5/8" diameter and then it goes to a reduction unit of some sort. There is no way anything other than a tooth belt would work/run on a shaft that small without slipping. It's a strange design for what ever reason... I donno? I have 3 Craftsman direct drive saws from the 80's that the blade mounts directly on the motor output shat. There is no reduction or slippage issue. Makes you wonder what they were thinkin' :blink:
Those speed controller are designed for a motor with brushes, like a router or skill saw, not an induction run motor.
Second, I see why they did the tooth belt design. The motor output shaft is about 5/8" diameter and then it goes to a reduction unit of some sort. There is no way anything other than a tooth belt would work/run on a shaft that small without slipping. It's a strange design for what ever reason... I donno? I have 3 Craftsman direct drive saws from the 80's that the blade mounts directly on the motor output shat. There is no reduction or slippage issue. Makes you wonder what they were thinkin' :blink:
I think this is a brush-type motor... the instruction manual includes a section on brush inspection and replacement. The small drive design may be due to the fact this is a 'contractor style' saw with the motor and belt system completely enclosed under the table (not hanging out the back), so maybe less room to work with.
fwiw. it may be beneficial to talk to a Delta tech on the subject. there may be a critical alignment, improvement, better belt, etc. that they know of.
I would think alignment would have to be spot on to minimize belt wear.
I would think alignment would have to be spot on to minimize belt wear.
that explains it
They used a high speed universal motor, 7000 to 8000 RPMs, then slow it down to the blade speed of 4000 or so. Your motor controller would probably work, BUT I suspect with some loss of power, even on full speed ahead. Probably about a $15.00 dollar experiment, if you get one at Harbor Fright where I got mine.
They used a high speed universal motor, 7000 to 8000 RPMs, then slow it down to the blade speed of 4000 or so. Your motor controller would probably work, BUT I suspect with some loss of power, even on full speed ahead. Probably about a $15.00 dollar experiment, if you get one at Harbor Fright where I got mine.
I think this is a brush-type motor... the instruction manual includes a section on brush inspection and replacement. The small drive design may be due to the fact this is a 'contractor style' saw with the motor and belt system completely enclosed under the table (not hanging out the back), so maybe less room to work with.
Crazy way to design a saw, there are so few teeth in contact with the motor shaft, pulley or whatever, how did they expect the belt to last. I would say 8000 RPM motor speed may even be on low side. :laughing:They used a high speed universal motor, 7000 to 8000 RPMs, then slow it down to the blade speed of 4000 or so. Your motor controller would probably work, BUT I suspect with some loss of power, even on full speed ahead. Probably about a $15.00 dollar experiment, if you get one at Harbor Fright where I got mine.
As a point of interest those belts are used to drive rotary printing press units, timing is so critical that we had the belts marked then split in half and installed the marks at 180 degrees to compensate for any variance in the tooth pattern.
Now you know what Warner sees in antique machinery.
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