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Ian B
12-21-2008, 05:14 AM
I recently bought an old belt drive 9" Startrite circular wood saw. It's a good quality machine, rise fall & tilt, cast iron table, heavy sheet steel base. The machine will take a 12" blade to give me more depth of cut (which I intend to fit), and there's space to install a more powerful motor if needed. It'll be used primarily for ripsawing of softwood.

The original configuration has the 9" blade running at 2,800rpm (there's a 1:1 belt drive from a 50Hz 3 phase 2 pole motor). This gives a blade cutting speed of about 6,800 fpm. I'm guessing that this was designed for use with carbon steel sawblades.

I tried to find the recommended cutting speed for a good quality modern carbide tipped blade, and haven't had much success. The 12" carbide blade I have is rated up to 7,000 rpm. This would result in a cutting speed of 22,000 fpm. I have seen references to bandsaws running at 4,000 fpm when cutting wood (I presume this is a steel blade, not carbide). Also chainsaws running at 5,500 fpm.

Does anyone have a recommended speed for ripsawing softwood (and hardwood, while we're at it) with carbide blades?

Also, the saw presently runs two Z section vee belts. My Scheppach spindle moulder uses 1" wide flat belts to transmit 3Hp. If I'm changing pulleys, I can go for flat or vee; any particular advantages to either in this application? The spindle pulley is limited to about 2 1/2" diameter.

Thanks,

Ian

torker
12-21-2008, 09:06 AM
Ian...that's an interesting question.
The only thing I can suggest would be to go look at saws with similar hp and blade size. Or I'm sure someone here will be able to tell you.

I've owned quite a few table saws...they've all used V belts...either two or three.
I've never been that impressed with the multi V belt drives. It seems after the belts get used a bit...you always have at least one that's useless as it stretches more than the rest.
It's too bad they don;'t use cog belts like we use on auto superchargers.
They may eat a bit of horepower but they last forever and never slip.
Russ

airsmith282
12-21-2008, 09:33 AM
hi there on your table saws its not so much the speed you need itts the amps of the motor idealy 12 amp or higher is best on tabler says with or with out carbid tip blades really makes no diference other ten when ripping hardwroods and really nasty hard woods, i never seen a carbide top blade for a band saw but i do have a larger delta band saw and idealy i can cut 6 inchs thicks of wood on it but it has to be taken slow which brigns us to the speed thing on any saw if you have to much speed you will burn the blade and the wood been there done it ..

if your cutting soft metals likse allim and brass on a miter saw for example you need 2 things 12 to 15 amps of motor and speed is not and iussed but if you dont have 12 to 15 amp motor then you wil burn out the saw been there done that as well..
thereal question is why do you need so much speed , horse power and amps are the 2 main components here that are needed not speed ,, 2000 to 2500 is more then enought speed after that you need 1/2 to 1 horse and 12 to 15 amp motor ..

the thicker the wood the slower you want that blade not faster so 2000 to 2500 is more then fast enough....

anyhow my 2 cents and some my own experiences as well

lynnl
12-21-2008, 10:17 AM
.....
It's too bad they don;'t use cog belts like we use on auto superchargers.
They may eat a bit of horepower but they last forever and never slip.
Russ

Russ, I once had a 9" Rockwell table saw that used a cog belt (about 1.25" W X approx. 5" dia). That thing went through belts like crazy. What would happen (I think) is wood chips would get trapped between the belt and the cogged pulleys and quickly destroy the belt.

It did have a lot of power, but in the 3 or 4 years I had it, it must've eaten at least 6 or 7 belts. Funny thing, when I lived in Selma Ala, a small town, I could get them locally, but when I moved to Shreveport LA, a much bigger town, I had to order them from Rockwell. Go figure. I started ordering them 2 or 3 at a time. ...plus they were a pain in the butt to install.

Duffy
12-21-2008, 10:51 AM
Delta, General, and even Craftex have 12" cabinet saws that work VERY well on 5 hp triple belt drives and can handle almost anything you feed them. Russ, for multi-belt drives, you are SUPPOSED to use a multi-belt SET not three similar belts. I have a 3hp double-belt 10" Craftex and it will march through 2" African Blackwood almost like oak. I have never seen a saw that could tell how thick the wood was! Carbide bandsaw blades are available, (and expensive,) but they are usually used for resaw work on exotics, some of which are high in silica and tear hell out of ordinary blades. If the wood is scorching, the plank may have a bit of sweep or the feed rate is too slow.
For ripping softwoods, you need a blade with LOTS of set, since the heat of cutting will release pitch which will build up on the blade, rub on the kerf edges and cause--Scorching!
Supposedly, the worst softwood to rip is Western Red Cedar. The reason is that the difference in hardness between the body of the wood and the knots is sufficient to cause chipping of carbide teeth. For extensive ripping, it is recommended by "experts" to use a power feeder to synchronize feed with blade speed. Your upper limit of blade speed, assuming the disc is properly tensioned and thick enough not to flutter, will be the ability to remove chips and dust from the kerf. I watched a water-flooded double-cutting bandsaw, (not carbide,) rip through a 4 foot by 40 foot hemlock log in under 30 seconds. I asked about the water and the answer was "it stops the wood from scorching and clears the chips."

MickeyD
12-21-2008, 10:51 AM
A lot of the new saws are using Poly-V belts and they work great. I have a 1.75HP hybrid saw with one and it is extremely smooth and quiet. It is amazing how well the tiny and delicate looking belts work.

torker
12-21-2008, 11:05 AM
Duffy...I've owned two Unisaws and a Craftex 10" saw..had troubles with all the belts.
I wasn't aware that you could get the belts as a set.
I do know that I replaced them all with automotive belts the same size and could never get them to match...after heavy use they would stretch at different rates.
As for cogged belts...I was thinking of REAL blower belts.
I ran my blown alcohol mud rail for years with them.
They got a constant diet of mud, rocks and whatever else flew up...and they did last.
The alu pullies...that's another story.

Ian B
12-22-2008, 04:45 AM
All,

Thanks for the replies.

I found a couple of sawblade manufacturer's websites, they recommend running carbide blades at between 10,000 and 18,000 feet per minute; that's about 200 miles per hour :-) That matches pretty close to the blade's maximum rated speed of 7,000 rpm (22,000 fpm).

I'm leaning towards a spindle speed of 4,000 rpm, giving 12,500 fpm on a 12". At that speed, running a 28 tooth blade and feeding work at the blade at a foot per second, each tooth will shave off about 6 thou. Even in thick wood, it shouldn't be anywhere near to choking the throats. Anything over that spindle speed, I'd probably be too scared to go in the workshop with it!

Matched triple Z section vee belts are probably the simplest way to go. 90mm on the motor, 65mm on the spindle. The thing attracting me to a flat (toothless) belt is that it's liable to jump off if the blade jams, but I can see that alignment is more of an issue.

On motor power; the saw presently has a 1.25 Hp motor and takes 3" cuts through oak easily. Using the larger blade will in theory allow 5" deep cuts. Carbide blades have a slightly wider kerf than carbon steel blades, so let's say I'm aiming to cut away twice the amount of material. This would double the power requirements. 3 Hp 2850 rpm motors are commonly available, but if there's space, I'll squeeze a 4 Hp in there. Still within range of what the 3 Z section belts will handle.

Poly vee belts are also worth me looking at. Do they jump off if a spindle jams? Anyone know how I can calculate the belt width required to transmit the power under these conditions?

Anyone seen this before? I'm not planning on getting one, but it's interesting to watch: http://www.sawstop.com/howitworks/videos.php Video 4 is nice - high speed film of a stop.

Ian

Your Old Dog
12-22-2008, 08:29 AM
I have a Jet 10" Cabinet Saw with a 2HP motor on it. You didn't say what you would be ripping for, either making pallets or furniture. If you're going to use a power feeder and make pallets you might want to go with a 4 hp motor. Otherwise, 2HP will cut a lot of wood in a hurry if you use the right blades.

I use Forrest Blades. I have a combination, cross and rip blades (actually about 11 or 12). If you're going to rip it is worth the expense to get a blade made for that purpose as it's much much easier on the saw. When I'm on a furniture project I never use the combination blade, it's only for quick projects and helps save my other two types for their special uses.

Don't know what your experience level is with wood but don't buy a blade that doesn't have harmonic suppressors cut into them. I nearly went deaf using cheap Home Depot type blades before someone put me onto the quality blades with the harmonic suppressors in them. The big difference in sound is when you aren't cutting and the cheap blades start to scream at you unless you want to power down between each cut. It will screw up your hearing in short order for particular frequencies. (Axe me how I know!)

BTW, you might notice that the Forest Blades use a much better grade of carbide. Only buy these if you don't mind taking them to someone locally to have them sharpened. They are too pricey for a consumable type blade.

torker
12-22-2008, 09:11 AM
YOD brings up a good point.
When I had my cabinet shop I used whatever I could get for blades.
Then the good quality, better engineered blades started to come out.
The difference was amazing.
I used to cut a lot of fire killed Western Larch back then.
Used it for raised panel doors and window frames.
It is a very hard wood to work with as the pitch content is "set" in various degrees according to how hot it got during the fire.
Some really nasty hard pitch that would gum up a carbon blade in minutes.
Seemed like the well engineered carbide blades cut much cooler and didn't have the problems with gumming up. Likewise with shaper cutters.

Willy
12-22-2008, 10:08 AM
Not wanting to hijack this thread, but Duffy does bring up an excellent point about matched sets when replacing v-belts.

I learned about matched sets long ago in different power transmission applications. Found out that matched belt applications would last almost forever. If replaced by a un-mtched set of belts with the same part # there would always be problems with unequal stretch and wear, as well as improper load sharing between belts.

Matched v-belt sets come in 2's,3's, and 4's, and probably more, but that's all I've ever had to acquire. They are cut from the same blank at the factory and you are thus assured a set that has the same characteristics and not just the same rough dimensions.

So remember whether it's a lathe, compressor, or anything that uses a multi-groove pulley arrangement, do yourself and you equipment a favor and use matched sets.
They cost more, and some parts guys won't know what you are talking about, but they are worth the trouble to find.

Of course everything I said goes out the window in an emergency, but save mis-matched sets for spares later when you have time to get the right ones.

Duffy
12-22-2008, 10:23 AM
Those sawstop units do work, and for a shop with employees, should be essential. You, the owner, can then hold your hand over your heart and say "yes your Honour, I did EVERYTHING possible to save that incompetent fool from hurting himself!" They have two minor drawbacks:- 1) you must replace the "cartridge assembly" if it ever functions-not cheap. 2) the blade is destroyed-also not cheap.

airsmith282
12-22-2008, 10:47 AM
Not wanting to hijack this thread, but Duffy does bring up an excellent point about matched sets when replacing v-belts.

I learned about matched sets long ago in different power transmission applications. Found out that matched belt applications would last almost forever. If replaced by a un-mtched set of belts with the same part # there would always be problems with unequal stretch and wear, as well as improper load sharing between belts.

Matched v-belt sets come in 2's,3's, and 4's, and probably more, but that's all I've ever had to acquire. They are cut from the same blank at the factory and you are thus assured a set that has the same characteristics and not just the same rough dimensions.

So remember whether it's a lathe, compressor, or anything that uses a multi-groove pulley arrangement, do yourself and you equipment a favor and use matched sets.
They cost more, and some parts guys won't know what you are talking about, but they are worth the trouble to find.

Of course everything I said goes out the window in an emergency, but save mis-matched sets for spares later when you have time to get the right ones.

hi there ok lets start class 101 here there is no such thing as perfectly matched or 100% matched anything, and yes this includeds v belt i dont car if there from the same roll or same batch of molten rubber when its all poured it cools a different temps and temps change in the pouring process, the same is in any kind of metal rods square hex and so one they all have different strengths and weak points they are al not exactly the same OD either in sides and not eactly the same id even in the same peice of bar or round stock..

now i do agree that when replacing belts in this case use to new ones that have the same id od and so on , never mix old and new belts...

but to say there eaxctly the same there not

the use of 2 pully belt system in a single belt and pully set up can go with you and can also go against you as well,and this depnds alot on on the bearing quailty in your spindle as well as the quailty of the motor and saw set up in this case as well ..

by adding in a second belt rig you not only increase belt tension but you incease all the side for tensions on the shafts and bearings as well and you also make the motor work a bit harder as well .. yes your lessing the wear and tear on the belts but you can also cause problems if you dont make the proper adjustments and allowences as well in order to compensat for the new set up..

Willy
12-22-2008, 11:22 AM
Matched belt sets are as close to being identical as is reasonably possible given the manufacturing process. Many applications involve multi-groove belt setups. To use belts from a name brand manufacturer that have the same belt part# that are not a matched set is folly.

The entire process of power transmission is compromised. Belt life suffers due to unequal loading and full power is not transferred because of unequal belt loading. I have seen this many times. You may be able to get away without matched sets in applications where full design power is rarely used but in those applications you could conceivably run a single belt and get away with that as well.

Ian B
12-22-2008, 11:24 AM
YOD,

Like everything else in my workshop, it'll get used for a whole range of stuff. Certainly rough work (although not with a power feeder, all hand feed) through to making bits for the better half's dolls house. I've always been from the "more power can only be a good idea" school; most times a 4 Hp motor will be overkill.

It'll be used for ripping & cross cutting hard & softwood, cutting plywood, MDF, blocks of African hardwood like azobe, padouk, bubinga, zebrano, ebony (yes, I know about the joys of breathing the dust from these timbers).

Harmonic suppressors - what are they? I've seen those curly slits that look like they're laser cut in some blades; are these the suppressors? I thought they were to prevent warpage when the blade heats up. I'll be very happy if I can keep the noise level down on the saw.

The poly vee belts look more and more appealing - I think I remember John Stevenson using a coventry die chaser for cutting the grooves in pulleys, but the poly belts I looked at have a 2.36mm vee spacing - which doesn't look like any standard thread...

Thanks,

Ian

jkilroy
12-22-2008, 12:36 PM
On a table saw that is going to be doing real ripping, production stuff, like three or four .75 sheets of ply at a time I want at much power as possible. I work on a powermatic with 7.5hp (originally 5) and a 12" blade and I can still load it down easily if the blade isn't fresh. The big saw is a 14" with 15hp, that girl will cut, don't get a jam with 4" solid, the saw *will* win. As far as speed goes, 4000 rpm and over at least.

Willy
12-22-2008, 01:46 PM
hi there ok lets start class 101 here there is no such thing as perfectly matched or 100% matched anything, and yes this includeds v belt i dont car if there from the same roll or same batch of molten rubber when its all poured it cools a different temps and temps change in the pouring process, the same is in any kind of metal rods square hex and so one they all have different strengths and weak points they are al not exactly the same OD either in sides and not eactly the same id even in the same peice of bar or round stock..

now i do agree that when replacing belts in this case use to new ones that have the same id od and so on , never mix old and new belts...

but to say there eaxctly the same there not
..

Perhaps I wasn't clear enough in my previous explanation of what a matched set is when I said that they are cut from the same blank.

When belts are manufactured they start as a wide hoop made to a certain diameter to coincide to a particular spec for a given application. They are then sliced off to the desired width. This belt will meet the specs for the intended application, as there is an acceptable range of movement in components to allow that belt to meet the requirements.

The reason a matched set costs more is because when that hoop of belt material is sliced to a particular width, those two, three, or whatever belts stay together. They are in effect the same belt. So yes, they are essentially 100% the same.

Sorry Ian for diverting your thread temporarily but I thought the matter deserved clarification.

Ian B
12-22-2008, 02:20 PM
No probs Willy!

If I switch to a poly vee belt drive for the saw, do you know how I specify a belt and width? I'm seeing PJ, PK, PL and PM sizes, of increasing vee pitches and belt thicknesses. Any recommendations on the size and width required to transmit 4 Hp, 2850 rpm motor with a 90mm pulley driving a 65mm pulley?

I can find enough information on sizing traditional single vee belts, not much on the poly vee belts.

Thanks,

Ian

Your Old Dog
12-22-2008, 08:55 PM
YOD,

Like everything else in my workshop, it'll get used for a whole range of stuff. Certainly rough work (although not with a power feeder, all hand feed) through to making bits for the better half's dolls house. I've always been from the "more power can only be a good idea" school; most times a 4 Hp motor will be overkill.

It'll be used for ripping & cross cutting hard & softwood, cutting plywood, MDF, blocks of African hardwood like azobe, padouk, bubinga, zebrano, ebony (yes, I know about the joys of breathing the dust from these timbers).

My 2HP will do all you say you plan on doing. You likely know you want the blade to cut at it's one speed and not choke it by really ramming the stuff through ! If you are aware of the hazards of the African woods you are probably more up to speed on wood working then I was giving you credit for.


Harmonic suppressors - what are they? I've seen those curly slits that look like they're laser cut in some blades; are these the suppressors? I thought they were to prevent warpage when the blade heats up. I'll be very happy if I can keep the noise level down on the saw.

Yea that's them. They kind of remind me of small musical cleff's laserd into the edge of the blade in a few places. They make the saw much more enjoyable to be around when you aren't cutting and searching for your next piece to feed through.


The poly vee belts look more and more appealing - I think I remember John Stevenson using a coventry die chaser for cutting the grooves in pulleys, but the poly belts I looked at have a 2.36mm vee spacing - which doesn't look like any standard thread...

Thanks,

Ian

I'm still using the original factory belts but also know something better is in order. I get vibrations in my saw that are really noticible in cold weather. After a long day in the shop and plenty of saw use the belts must warm up and run smoother because there is a marked difference in the vibration level.

Good luck and have fun :D

torker
12-22-2008, 09:03 PM
You guys are making me homesick... My 8" jointer, tablesaw and planer are all still out in my covered "motorsickle/quad/sled" parking garage. All covered up and still taken apart from our move here 1 1/2 years ago.
I still have boxes of routers and a lot of other woodworking stuff....all still unpacked.
The plan is to close in part of this garage so I can make some wood chips again.
The only real holdup is the amazing cost of concrete right now.
Between the addition I need for my welding shop and the woodworking shop...it's right at $14,000 for concrete. Ouch!

jdunmyer
12-22-2008, 09:42 PM
FWIW: depending on which blade I use, my sawmill runs between 7000 and 8000 FPM on the rim. My mill turns at only about 480 Rpm in the cut, which is a bit slow compared to most.

In production saws like gang rip saws, I've been told "5 Hp per blade". We have 2 tablesaws, a 2 Hp Craftsman and a 5 Hp Delta. There's no comparison when you're ripping hardwood. NO comparison.