Replies

1. 
   forestgirl | Aug 11, 2003 11:43pm | #1

   Probably, but if you want a real thrill, order or pick some link-belts material.  Wouldn't be surprised if they made even a PM 65 run better.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

2. 
   SCFrankland | Aug 12, 2003 02:20am | #2

   Agreed get the link belts they are worth the extra money.

   Scott C. Frankland

   "This all could have been prevented if their parents had just used birth control"

3. 
   rckendall | Aug 12, 2003 05:19am | #3

   Davod.

   I've used the link belts myself, but past experience has taught me that the multiple belt systems use "matched sets" and I would question the ability of the linked belts to do this. It all gets down to proper tension of each belt.

   Richard

1. 
   forestgirl | Aug 12, 2003 06:53am | #4

   Some multi-belt saws come equipped with link belts as standard equipment.  Why would a link belt be any more difficult to match than a regular belt?  Each link is a standard length, and the material is made for industrial applications, so why would it not work for our saws?  forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

1. 
   rckendall | Aug 12, 2003 04:30pm | #8

   Forstgirl,

   I was not aware that link belts were furnished on multi-belt equipment. My background has been somewhat like Tooldoc, who further explained the concerns. I find this site very informative but sometimes it's not worth trying to re-invent the wheel. IMHO, when a good piece of equipment is designed to use xyz and it has worked for umpteen years, why would we, with our shallow knowledge of the design, try to improve on it?

   Don't get me wrong, I think it is great to think about and ask, but if there is doubt, then go with what has already proven itself over years.

   Thanks also to Tooldoc for elaborating.

   Richard

2. 
   Manchild | Aug 12, 2003 07:13am | #5

   sooo, Should I go to the auto parts store and buy a couple of good matched belts? I could match them by comparing the length while stretching them.

1. 
   rslatm | Aug 12, 2003 04:33pm | #9

   Unless your autimotive store also carries industrial belts it will be a waste of time.  Automotive belts are different than industrial belts.  I see no problems with using the fenner belts in place of matched belts. I've seen them on rock crushing machines that had a dozen belts. I don't think the fenner belts are the solution to everything.  I buy my belts from a local power transmission company or mcmaster.com  I also never pay the money to buy matched belts. Belts are made in molds so they should be consistent especially if you buy multiples at the same time of the same brand. Woodworking machines aren't that high tech except for specialized  production machines, CNC routers, high speed moulders and our 12" Wadkin uses special flat belts for the 6,000 rpm spindles.  For cabinet saws I use  x cog type belts not fenners.  The thing about the fenner that people seem to not mention is the lack of memory.  On a contractor saw the memory  factor creates a bounce in the motor wich results in slippage. This slippage occurs because the motor uses gravity to create the tension on the belt.  On a cabinetsaw the tension is fixed so you don't get the bounce factor so no slippage.

   http://www.fennerindustrial.com/applications/ptp_wood.html

2. 
   eokie | Aug 12, 2003 06:01pm | #15

   Be careful on the interpretation of the word "matched" belts, per se. The mfg. likely is saying that when there is more than one belt on a machine, replace - all - belts at the same time, even if only one broke, or is "bad."

   It is the uniformity that is important, i.e., an old stretched/worn belt will be different than the identical new belt. Also, if one belt is bad, high probability says the next one going bad is in the near future. For the effort involved, change 'em all when things are torn down.

   Another example of "matching" is automotive tires - it's not a good idea to replace only one tire on a given axle, front or rear.

4. 
   ToolDoc | Aug 12, 2003 07:14am | #6

   David: Listen to Richard and replace your Belts with a Matched set of belts,the reason IM saying this because Delta Highly Recomends Replacing Belts on there UNI SAW with Matched sets of Belts & Im sure PM does too..IM not saying that Link Belts are not good but I think this is one time that matched belts are a better choice..Being a Maintenance Mechanic & servicing all types of major Equipment I have found that using the correct belts does make a Major diffrence in the performance of said Equipment..

                        ToolDoc

5. 
   DJK | Aug 12, 2003 03:45pm | #7

   My 1964 PM 65 cabinet saw uses three 4L belts as does my 1985 PM66. Automotive belts have a different taper than USRM spec machine belts. I have used the red link belts on a Unisaw. They will work but they ride high on a sheave designed for a 4L/A size belt. Mine rubbed on the under side of the table at full blade height. Red link belts need a higher tension than a standard belt, read the instructions. Higher tension will result in premature arbor and motor bearing failure. My choice if the factory belts aren't used are AX type belts or a RAW EDGE 4L/A section belt. A raw edge belt will transmit much more power than a standard wraped edge belt given the same size sheave.

   Dave Koury

1. 
   Manchild | Aug 12, 2003 04:38pm | #10

   DJK, Thank you for the info.. I have a few more questions though.

   Someone put a two belt sheave on the motor. The arbor still has three. Should I find/install a triple?

   I don't have a source for Powermatic parts. Do you know where I can buy these items from who knows what needs to go on here.

   Thanks for you time, David

1. 
   ToolDoc | Aug 12, 2003 04:52pm | #11

   David: PM is mfg by WMH Tool Group you can get info & contact them at this site..

   http://www.jettools.com/             ToolDoc

1. 
   Manchild | Aug 12, 2003 05:15pm | #12

   I went to the site but there is no phone # just a contact through e-mail.

   Looks like a big tool co. selling a lot of tools.

   Sometimes I just want to call someone and talk to them, you know what I mean?

   I'll e-mail them.

1. 
   ToolDoc | Aug 12, 2003 05:47pm | #14

   David: try this number for technical service Mon~Fri 7AM~4:30PM Pacific time

     1-800-274-6846      IM sure they will have answers for your Questons..

                                            ToolDoc

2. 
   rslatm | Aug 12, 2003 05:16pm | #13

   PM changed to two belts instead of three  years ago.  Two belts is plenty.  We have 10 hp saws in our shop that only have one belt and we have no problems. I used to be a service tech and had direct contact with Delta. They did a study and found that one belt would be fine for a Unisaw but declined to change it because it would be perceived as cheapening the product even if three belts is over kill.

3. 
   DJK | Aug 12, 2003 06:16pm | #17

   When PM obsolete a part they will sell them to Redmond in Atlanta. http://www.redmond-machinery.com

   Some think it's one belt per horsepower, so what if it's five or seven and a half horepower, add more belts. The amount of power transmitted is based on the type of belt and the size of the sheave The larger the sheave the more power transmitted per a given type of belt. There is more surface area for the belt to grip. Friction is the force applied.

   I'd do it right and purchase a three groove sheave.

   As for PM using two belts, they are 3VX not 4L/A section. 3VX is a larger belt made to transmit more power per a given sheave size.

   Dave Koury

   Edited 8/12/2003 11:24:58 AM ET by DJK

4. 
   TKanzler | Aug 12, 2003 06:56pm | #19

   david - Here's the lowdown on belts, from something I posted elsewhere a while back. 

   Fractional horsepower belts (FHP), which are designated 2L through 5L, are meant to be operated singly, and generally at lowish power. They are also shallower, and have less cord, than standard belts, and are thus more flexible. The most common on woodworking machines, when FHP belts are used, are 4L, and are 0.5" across the top. Standard belts use the A through D designation. A-belts are also 0.5" across the top (D-belts are 1.25" across, sizes increment by 1/4"), but are deeper and have more cord. They can handle higher power than fractional, and are the type generally used with multiple-belt drives. Some manufacturers, Gates in particular, don't even match them anymore, since manufacturing tolerances can be held much tighter than in the past, eliminating the need. Belts designated as 3V, 5V and 8V (or VX, where X indicates notched) I believe are referred to in Europe as "wedge belts", but I don't know the generic designation. They are capable of the highest hp per belt, and can be used in sets. These are what Powermatic uses. How much power a belt can transmit depends on lots of variables, including pitch diameter of the smaller sheave, distance between sheaves (which effects both angle of wrap around the smaller one, and how frequently the belt is flexed), the speed, and the sheave diameters (at same ratio, larger increases belt speed, reducing tension, but possibly causing dynamic problems, a la vibration). From a Browning (drives, not guns) design manual, using a 3" pitch diameter smaller sheave at 4000 rpm (current Unisaws use 3.5" PD on the motor, and 3" on the arbor, if memory serves), the power rating of a single 4L belt is 1.37 hp. An A-belt on the same sheave and speed has a rating of 3.52 hp per belt, and a notched version is rated at 4.4 hp. A 3VX belt, which is only 3/8" across the top, has a rating of 5.41 hp per belt.  [Edit: These basic belt ratings are taken from tables, and are valid for the sheave size and speed stated, but for other sizes and speeds the ratings vary greatly.  For example, a 4L belt rating varies from a high of 2 hp to less than 1/10 hp, depending on sheave size and speed.]Naturally, that's not the end of it. After corrections are applied for geometry (short belts reduce the rating, as does loss of arc of contact due to high ratios), overload factors, even prime mover type (single-cylinder engines are not as smooth as single-phase motors, which in turn are not as smooth as 3-phase motors, for example), hours per day of use along with duty cycle when operating, and desired longevity (all of which is also subject to the designer's experience and judgement), you could end up operating at one half of the tabulated values, or less. As far as why a Unisaw uses three FHP belts, I'd guess that it's because it was invented in 1938 when v-belts were new, and made of cotton and natural rubber, and that to transmit the 1 hp of the original "bullet" motors (1.5 hp for the 3-phase version) it took 3 belts to get good power transmission and belt life. Remember also that the original saws operated at about 3150 rpm, with 1750 rpm motors, so the lower arbor speed requires higher belt tension (on the "loaded" side) for the same hp, with a smaller arc of contact due to the higher ratio). With the advent of higher hp motors, but better belt construction and materials, Delta (educated guess, here) elected to stay with FHP belts (they're more flexible than A-belts, and I believe they still have them milled a little narrower than standard - mine measure .450" wide), and run them loose to keep vibration in check, which I do, and it works (very loose, and they never slip). Jet copied the Unisaw, almost down to the casting flaws, so they use 3 also. Powermatic, I'm guessing, believe they found a better way with a pair of 3VX belts, either for economic or performance reasons (reduced vibration, maybe; I couldn't possibly know for fact), but they very well may have found a better way. But don't discount economic reasons; machining custom sheaves with two 3/8" grooves is almost certainly cheaper than sheaves with three 1/2" grooves, all other things being equal, though 3VX belts may be more costly. As far as other brands, a pair of A-section belts could easily handle 5 hp, with good belt life, depending on speed and sheave size, of course. And for that matter, 4L belts can handle more power than they should, with reduced life, but that doesn't matter on machines that infrequently run under heavy load, like jointers, drill presses, and bandsaws. A furnace blower using a 4L belt has to run at full load for thousands of hours, but it would take most folks several lifetimes to put a thousand hours of actual heavy wood cutting on a jointer.

   It's up to you, of course, as to whether or not to replace the motor sheave and use 3 belts. 

   Be seeing you...

   Edited 8/12/2003 12:08:26 PM ET by Tom Kanzler

1. 
   ToolDoc | Aug 12, 2003 07:20pm | #20

   I guess we could go on & on about v belts VS Link Belts forever,But for some Great info on Belts check out this site~

   http://www.gates.com       they have a Gates belt drive PM & safety manual you can either order or download a PDF..

                                             ToolDoc

2. 
   Manchild | Aug 12, 2003 08:05pm | #21

   Thank you Tom, I had to chuckle after reading your post. You obviously know a lot about belts.

   O.K. This what I did. I called up the people who still make Powermatic saws and ordered two belts.

   I also asked about the vintage of the saw and was told it was manufactured in the late fifties-early sixties.

   I still haven't read all the posts, but I will. Thanks to all of you. I think we knotheads like our machines very much.

1. 
   TKanzler | Aug 12, 2003 08:39pm | #22

   If you're buying belts from Powermatic, you should probably compare the diameter of the present motor sheave with what it originally had (they should be able to tell you what it had).  If it's not the same, then the belt length will not be right.  Good luck.Be seeing you...

2. 
   Manchild | Aug 12, 2003 11:29pm | #23

   I didn't think of that. I'll bet there O.K., but we shall see.

3. 
   MarkRoderick | Aug 13, 2003 07:45pm | #24

   Can't you provide more detail than that? (a joke)

6. 
   HowardAcheson | Aug 12, 2003 06:10pm | #16

   Are they used as pair? If so, you should get a "matched set". Personally, I don't see any need for link type belts on a cabinet saw.

7. 
   Elcoholic | Aug 12, 2003 06:27pm | #18

   I put 3 'identical" new belts on my 5hp planer/molder that were not matched.  Only one is tight and the other two flap causing a whole lot of vibration which can't be improving the quality of the cut.  It's on my list to go to back to Mesa Bearing and buy a matched set.  Don't make the same mistake I did.  I don't think multiple link belts are the right way to go.  I doubt you'll find matched sets through an auto parts store since there's no auto motive application requiring them.  Try an industrial bearing and/or power transmission supplier, maybe even Grainger.

   John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne