Replacing the Drive Belt with one from Bandsaw-Tire-Warehouse

[dusty]

I don't know exactly why, since I already had a new drive belt spare from Shopsmith, but I bought and installed a new belt from Bandsaw-Tire-Warehouse.

Installation did not proceed as smoothly as I thought it would. Removal of the old belt was typical. Installation of the new belt was quite a bit more difficult. To make sure I wasn't doing something wrong, I put a Shopsmith belt on. Went as smooth as I would have expected. Took that belt off and tried again. Still difficult but I got it done.

Speed checks are inconsistent with past experience.

Before the change: High Speed was 8504 rpm and Low Speed was 1198 rpm.

After the belt change: High Speed is 7050 rpm and Low Speed is 1272 rpm. At low Saw Speed the drive shaft is at 4066 rpm.

I have made NO ADJUSTMENTS as of yet but the High Speed Stop appears to be dead on.

The drive belt, at Low Speed rides too high in the sheave (about 1/16" above the sheave).

The change in physical belt characteristics (old vs new) along with the fact that there have been no adjustments made are undoubtedly the reasons but I was (am) surprised at how much the differences are. Neither the original speed readings or the new speed readings are per advertised specifications (700rpm to 5200rpm).

[reible]

New belts seem to take a bit of time to "wear" in. I'm thinking your observations are with it still being "new" is that correct?

Ed

[dusty]

Yes, Ed that is the case. The belt is brand new. It doesn't have but a few minutes of run time.

The Mark V runs well and sounds good. It is just the radical change in numbers (rpm) that intrigues me.

Shopsmith numbers 700rpm to 5200rpm (4500rpm span high to low)

New Belt numbers 1272rpm to 7050rpm (5778rpm span high to low)

Old Belt numbers 1198rpm to 8504rpm (6306rpm span high to low)

It seems to me as though there is more involved here than just the change in belts.

[dusty]

The drive belt that was replaced by the new belt from Bandsaw-Tire-Warehouse is an old Shopsmith belt (504193) that was manufactured by Pirelli and is marked "Made in Italy". It measures almost exactly 26" in outside length and is less than 1/2" (.489") in width (11/32" on inside).

[JPG]

If the 'old' belt is less than 1/2", the speed range should be 'higher' as you observed. Ditto if 'short'.

You mention the belt rides high on the sheave at 'low'. Where does the belt ride on the motor pulley at fast?

You state the high speed stop is 'dead on'. Does than mean with the 'new' belt as well as the 'old' belt? That implies the new belt also rides below the motor pulley rim at fast. Not sure I understand how that is possible.

You mentioned 'difficulty' installing the BTW belt. If the belt is 'wider', it would act like it was 'short' putting it on the motor pulley since it would not drop as deeply into the idler pulley.

What did the BTW belt measure outside?

My made in Italy belt also measures 'short' as shown(posted) a few days ago.



We know 'too much'. 'Normal' reaction would be "Gee, it runs so much smoother with the new belt", and that would be the end of it!

[dusty]

If the 'old' belt is less than 1/2", the speed range should be 'higher' as you observed. Ditto if 'short'.

You mention the belt rides high on the sheave at 'low'. Where does the belt ride on the motor pulley at fast?

You state the high speed stop is 'dead on'. Does than mean with the 'new' belt as well as the 'old' belt? That implies the new belt also rides below the motor pulley rim at fast. Not sure I understand how that is possible.
You don't understand because the statement is ambiguous. The dial indicator is dead on but the belt rides high in the sheave at one end and low in the sheave at the other end. I apparently still have either 'work yet to do' or 'must be patient until the belt wears in'.

You mentioned 'difficulty' installing the BTW belt. If the belt is 'wider', it would act like it was 'short' putting it on the motor pulley since it would not drop as deeply into the idler pulley.

What did the BTW belt measure outside?

My made in Italy belt also measures 'short' as shown(posted) a few days ago.



We know 'too much'. 'Normal' reaction would be "Gee, it runs so much smoother with the new belt", and that would be the end of it!

Your last comment may be "dead on".

The belt from BTW measures wider than 1/2" (I think by 1/32" but may be 1/16") I'll post that when I can go measure it.

[dusty]

If the 'old' belt is less than 1/2", the speed range should be 'higher' as you observed. Ditto if 'short'.

You mention the belt rides high on the sheave at 'low'. Where does the belt ride on the motor pulley at fast?

You state the high speed stop is 'dead on'. Does than mean with the 'new' belt as well as the 'old' belt? That implies the new belt also rides below the motor pulley rim at fast. Not sure I understand how that is possible.
You don't understand because the statement is ambiguous. The dial indicator is dead on but the belt rides high in the sheave at one end and low in the sheave at the other end. I apparently still have either 'work yet to do' or 'must be patient until the belt wears in'.

You mentioned 'difficulty' installing the BTW belt. If the belt is 'wider', it would act like it was 'short' putting it on the motor pulley since it would not drop as deeply into the idler pulley. I suppose you are right but the new belt is 3/8" longer.
What did the BTW belt measure outside? Wider than 1/2" (I'll measure it later).
My made in Italy belt also measures 'short' as shown(posted) a few days ago.



We know 'too much'. 'Normal' reaction would be "Gee, it runs so much smoother with the new belt", and that would be the end of it!

Your last comment may be "dead on".

The belt from BTW measures wider than 1/2" (I think by 1/32" but may be 1/16") I'll post that when I can go measure it.

[JPG]

High Speed Adjustment:

Step one: Adjust speed control until the motor belt sets about 1/4"
(+-) below the motor pulley rim.

New belt = repeat step one.

Then adjust the stop. Then set dial.

Then check belt positions at "fast" and "slow" and dial indication at slow.

I do not see any mention of step one above.

[dusty]

I am back to step 1 with the belt replacement. I needed information that I could not get with the belt installed.

The attached drawing shows the profile of four belts. The two that are dimensioned in the drawing are new. The larger one being the belt from BTW and the other an unused (unmounted) belt from Shopsmith. The other two are used belts that I retained after being replaced just because I do that.

The belt from BTW, it has been stated by BTW, was manufactured according to original Shopsmith specifications.

I'll post the belt lengths (as a PS) a bit later.

[dusty]

I decided that I was no longer willing to spend time attempting to make the belt that I just bought from Bandsaw Tire Warehouse work like I believe it should. It works and may be totally acceptable to some but it now hangs on the wall in my shop as an "emergency spare".

I installed a new Shopsmith belt (504193 made in Mexico) in the Shorty. The belt width varies a little (.538" to .541") and is 26 1/4" long (outside diameter).

After performing the high speed adjustment, the drive shaft RPM is 5262 at high speed and 876 RPM at low speed. These numbers are a bit different than the Shopsmith stated operating speeds of 5200RPM and 700RPM respectively.

With that in mind, the motor RPM is not as advertised either. Unloaded (motor belt removed), the motor turns at 3594RPM. Advertised speed being 3450RPM.

With a load (motor belt installed), the motor turns at a high speed (on the dial)of 3534RPM and 3581RPM at slow speed (on the dial).

I am going to leave everything as it is for right now; to allow the motor drive belt to get broken in. Later, I may twink the high speed adjustment so as to lower the low speed RPM to something closer to 700RPM. This machine (the Shorty) is used most heavily in the drill press mode where lower RPM is desirable.

I am compiling an order from Shopsmith right now. I need to get it through "financial management" first but when approved the order will include a new belt (504193) from Shopsmith. I wonder where this one will have been made. I have had belts from Italy and Mexico and one with number 504193DF (location unknown).