Having trouble selecting a belt drive for my router. :(
To many different options & sizes. :drowning:

I've downloaded & tried several manufacturer's software selection tools but most are made for constant RPM & HP designs not so much for servo applications.

I'm running 300oz-in cont & 1000oz-in peak @ 2:1 (3500rpm->1750rpm)

Need to keep the pulleys as small as possible due to space restrictions.

Just wondering what other people are using.

What brands? Gates, Goodyear, Browning?

Also is it best to use a smaller pitch to prevent cogging and keep the drive running smooth?

THANKS!

Chris

Good question azsigns. I will be waiting for an answer too.

The other day I went to a store that only sold belts and pulleys. By the time I came out I was feeing like an idiot. There was so many choices and variations of the same thing. The sales preson although he thought he was helping me, asked all sorts of questions about my machine. I didnt have a clue, I felt like saying Ill have one on these and one of those and please skip the questions.
I have just about descided that if it looks like it will work, and looks strong enough then thats what I will use. The about right method.

Just to give you an idea. (from the Gates Power Grip Timing Belt Cat)

Pitch Selection Guide

units in HP , RPMS of faster shaft
RPM --------Pitch Size---------------
******MXL . 080***XL .200***L .375
870-------.02-----------.10---------1.25
1160------.03-----------.15--------1.75
2500------.07-----------.30--------3.50
3500------.09-----------.45--------5.00


If someone could convert your in oz ratings to Hp I could give you more info.

Hi, we run Gates GT timiing belts with taper lock hub on our pulleys.These are driving some serious servos on a cnc center that machines heavy cast aluminum at high feed and spindle speeds (this is a production machine) As an idustrial mechanic i can honestly say that Gates products seem to be the best out there.......but that is of-course my opinion

I was looking at Gates GT2.

Very expensive pulleys!!!
Belt cost is not bad.

Around $180 for the 25mm belt & pulleys (1.25" & 2.5").

Are pulleys available from other mfg for this belt?

Chris

Chris, As long as the "pitch" and width of the pulley are same (width can be bigger), you should be able, in theory to use any pulley mfg. just be a little careful of the loads you intend to put on the pulley, the cheapie ones bend and flex if belt tension is too tight.......

A good selection of pulleys, but I don't think they have the 25mm belts.

https://sdp-si.com/eStore/

Thanks ger21.

I found the site just at the moment you posted!

Turns out that sdp is licenced by Gates to also make the GT2 pulleys.
Much lower cost but only have up to 15mm.

Turns out the Gates GT2 pulley is just a little different from standard pulleys on the same pitch.

chris

Are you sure the 15mm isn't big enough? We have a Schelling beam saw that uses GT2 belts for the saw blades. The main blade I think uses a 25mm belt, but it's something like a 15hp motor. I believe the scoring blade uses only a12 to15mm belt, and it's still at least a 2hp motor. These belts are pretty strong. sdp will send you a free catalog with a lot of info on GT2 belts and applications.

Pulley diameter has an effect on transmittable horsepower. Regular gearbelts or synchronous timing belts are likely the best choice because they are quite flexible on small pulleys. I don't know about the flexibility of the GT2 belts on small pulleys. I don't think it would be recommended.

A 1" wide 3/8" pitch belt (L series gearbelt) has a rating of 1.8 hp with a 3500 rpm driver running at 2:1 but there is a warning that this pulley is smaller than recommended and a reduction in belt life will occur if loaded to the max continuously.

These same belts are available in 1/2 or 3/4" widths. The rating would be valid for metal pulleys, which would typically be cast iron.

The danger of using too small of a pulley are the chances of the belt jumping cogs when the motor accelerates quickly. The problem is exaggerated if the pulleys run close to one another, because the arc of contact is reduced on the small pulley.

BTW, Browing or Gates gearbelts are interchangeable.

Hi Inventit,
I dont know how to convert in. oz. to hp but I understand that torque can be calculated from hp. There is a very handy freeware application here http://www.joshmadison.com/software/convert/ called Convert, but it can only do torque to torque and power to power, no combination in between.
Splint

The horsepower is a measure of ... power!

1 metric HP is about 735 watts.
1 english HP is about 746 watts.

Power is torque times angular velocity.

In metric units (and I do hope I get the unit names and designations right this time):

Arvid

So to convert from torque (oz. in.) to hp or back, you also need to know the speed where that torque is produced (not the maximum speed and torque of the motor, but the speed and torque that can be produced simultaneously).

If you don't want to do the math above, here's a shortcut:

Power (in HP) = torque (in oz. in.) * RPM / 1,000,000.

That is, if I did my math correctly :)

Arvid

Just done the belt and pulley thing here :)!

I ended up with 25 mm wide AT5 Synchroflex Timing belts as I'm using 700 oz Servo's on a Knee Mill retrofit.

It was interesting to see the recommendations the PC program spat out at the belt place dependant on the amount of belt wrap V's the centre distances between pulleys.

The AT5 belts is rated to almost 20 HP under ideal conditions but in my application this drops to about 1.3 HP due to the limited number of teeth engaged.

I initially thought 16 mm wide would suffice but after consulting with their engineer and crunching some numbers we arrived at the 25 mm belt.