Member postings for Simon Williams 3

Hi again Jon - not that I'm obsessive about this, but...

You might find that the bargain basement vee belts selling on price on Amazon don't conform round the little pulley -groove shape of the lower speed driver pulleys. I bet these pulley sheaves are less than the minimum bend radius of the normal bog standard construction vee belt, and you may need something a lot more pliable.

My local bearing shop has sold me vee belts for funny applications before, and while they certainly cost more than you have mentioned, they did the job and lasted a sensible time. Those poor abused vee belts on a ride on lawnmower deck have a hard time...

If you're not happy with the results with your el-cheapo belts (poor grip, poor service life or possibly both) it might be worth your while to chat up a local bearing/transmission specialist shop and get them interested. Of course if Amazon does it for you good luck!

Rgds

Simon

And this is what the individual parts look like off the mill

Here is a close up of the table stop parts in situ

Here's a picture of the screw operated belt tensioner. The longer column clamp bolts and packers (stacked nuts) on the right of the head stock are simply so you can get a spanner onto the clamp bolts without amputating your knuckles.

Assuming you let the arm carrying the middle idler pulley "float" i.e. rotate about the axis of the column, the tension in the two belts is nominally equal. So you just do up the belt tensioner to tighten both belts the same amount.

I use mine mostly as a drilling machine, because it has a no 3 morse taper up the spout. It's a perfectly serviceable milling machine, but I haven't used it as such since the day I bought a Tom Senior vertical mill.

By and large I use the mill/drill for drilling holes where you need the spindle running at less than 200 up to 800 rpm (drilling 10 mm dia up to say 25 mm or so). In these conditions the belt from the motor is used around a very small diameter pulley, whereas the others are around bigger sheaves. This means that the friction between the smallest pulley and the belt is what governs how much torque is actually transmitted to the belt drive. You need a fair bit of tension to get the belt to sit properly in the groove of the tiny pulley on the motor shaft.

I've found my vsd allows me to do this speed variation without swapping belt positions. By using a VSD compatible motor (now there's a long story!) I get enough torque to do what I want to do and the belt stays put in one set of grooves. Yippee!

At higher speeds the whole machine is over-designed anyway, so transmitting enough torque to drill say a 2 or 3 mm hole can pretty much be done without any significant tension in the belts at all.

I tried uploading some piccy's - haven't worked out how to do it yet. I bet there are some instructions here somewhere in the forums.

Simon

And the other comment I wanted to make is that on my machine there is plenty of movement of the motor on its mounting plate to tighten the belts successfully with the belts fitted I've shown, without carving out a bigger hole in the top guard. That might be why one of the belts is an A30, not an A31 but since these are the originals I've never bothered to experiment and see the limits of the belt length tolerance.

Simon

Hi again, the other modification I did to mine fairly early in its life was to fit a screw jack to the belt tensioner. At its simplest it's just a bit of all-thread from a bracket screwed to the RHS of the head casting to a pivot welded on the side of the motor mounting plate. The motor and its mounting plate swivel on two bolts on the LHS of the head casting. Originally there was a silly sliding peg and grubscrew affair to push the motor mounting plate backwards and tighten the belt.

Quite apart from this needing at least three hands to do, one of the main advantages of a belt driven machine is to be able to set the belt tension so the drive is firm enough to turn the cutter, drill etc, but if it all goes horribly wrong the belt slips rather than breaking things. Especially useful for drilling big holes! My experience with the peg and grubscrew arrangement it was originally fitted with was it was impossible to tighten the belt enough to drive properly - it's got a 1 hp motor and if you're drilling inch and a quarter holes you need the belt tight enough to transmit the torque of the motor. Otherwise you just keep stalling the spindle and chipping the edge off the drill.

If you're interested I'll show some photo's - it's a bit crude and made by a blacksmith (and an agricultural one at that!) but you'll get the idea. If I can work out how to upload piccy's...

Best rgds

Simon

I bought one of these machines 30 years ago from Graham Eng in West Bromwich, so it's got their Alpine nameplate on it not the RP-25 model number. But I'm pretty sure it was their model RP25 all that time ago, and the bigger one (RP35?) was too expensive, so I'm fairly certain it's the same machine. The pictures look the same ...

Anyway the point of this is that the two belts on my machine (which are the originals) are marked:

From spindle to idler cone pulley is marked A38

From idler pulley to motor pulley is marked A30.

Hope this helps, I wouldn't use link belt whizzing around that close to my hair line for all the love in the world - unless of course you always put the belt guard back after resetting the belts!!!!!

I've just converted mine to a three phase motor and a VSD. Great improvement, much more controllable, only sorry I didn't do it years ago.

Best rgds

Simon