Flat belting for transmission use on models?

[Tony Bird]

Hi,

Has anyone had any experience of using flat transmission belts on pulleys? If so ant information would be greatly appreciated. I have just made a pulley for use on my large oscillating engine and would like to use a flat belt drive.

The pulley was made from a serviette ring bought in a charity shop yesterday for £2.49 for 4; the intention is to make the other three rings into a transmission system and it would be nice to use flat belting if it is practical. Interestingly the rings under the plating are nickel silver as I though they looked a little cheap I thought they would be brass so they were EPNS!

Hopefully the following photographs will be found interesting.

















I hope someone can help.

Regards Tony.

 

[Tin Falcon]

You should not have a problem with flat bet. But the pulleys should be crowned else the belt will likely slip off to the side and fall off.
BTW nice work .
Tin

 

[goldstar31]

Probably going over to recent questions raised in the Madmodder website on - belt sanders will answer a few problems. After all a belt is a belt. From my own experiences on older lathes, it doesn't need to be a specific radius to work. Again, it depends on what material is used.

Somewhere, would you believe- is how the Myford can be converted to flat belts. Hemingwaykits is the supplier.

My old copy( 1942) of Machinery goes into 'endless length' to discuss the matter.

Probably getting the belt off a cheap Chinese belt sander or combined abrasive wheel and belt sander gizmo would be a good starting point.

Then- if you recall, are rosins to minimise slipping.

It's all part of the Industrial Resolution.

Norman

 

[ShopShoe]

Building on what Goldstar31 said:

My Dad liked to tell a story about rigging engines to various farm tasks in the 1930s where rope would be wound around a too-small pulley for as many layers as needed, then the whole thing would be coated with something like shellac.

The point is this is not that critical. I have made crowned flat-belt pulleys as an experiment and they work pretty well. There is a discussion somewhere online about making rollers for (woodworking) belt sanders on a wood lathe that discusses how to guestimate the amount of crown. I'm sorry, but I can't find the link today.

--ShopShoe

 

[modeng2000]

Tony, you are a master at putting things to different uses.
A nice bit of lateral thinking.

John

 

[vederstein]

Question:

Why does a crowned pulley even work? To me it seems that the crown would "pull" the belt to one side or another. On some of my engines, I made the crowned pulley/flywheel as per print. When I tried to run a belt, it always slipped off.

So I made a flat pulley with side guides.

Perhaps someone smarter than me can explain what's going on?

 

[goldstar31]

I'm not smarter but merely able to understand the 6th Proposition of Euclid( I think?)

It deals with the concept of right angles and if your belt was not at right angles, it will come off.

I do understand how wire ropes were used to send coal down rails to coaling staithes on the River Tyne- and they used raised lips on the rollers. My father used to 'socket' the ropes.

Does this help?

Cheers

Norman

 

[mcostello]

A trapazodial crown would be easiest to make, it's just a slight angle on the side. The pulley could be mounted on a mandrel, angle cut then pulley removed and turned around and the other side cut keeping them identical.

 

[deverett]

I've tried using a green flat plastic belt supplied by one of the traction engine casting suppliers - useless.
I've got some thin leather which when cut into thin strips and scarfed (well, sort of) and glued works well. Just add two or three stitches at the joint to make it look more authentic.

Dave
The Emerald Isle

 

[Herbiev]

A strip of leather from an or handbag and ends stapled ( short staples) has worked for me. The pulleys just need a very slight crown because belts always ride up to the highest point.

 

[Charles Lamont]

Somewhere, would you believe- is how the Myford can be converted to flat belts. Hemingwaykits is the supplier.

I think you will find that kit is for poly-v.

Here's an explanation:

http://woodgears.ca/bandsaw/crowned_pulleys.html

 

[goldstar31]

Apologies Charles but one set of belting is pretty similar to another.

Frankly I hate the whole damned thing in reality. It was about 1941, I was 11 and I was returning from the local flea pit having seen the AJ Cronin's film The Stars Look Down. My father was in our tin bath in the living room cut to shreds having slipped on a conveyor belt under ground. He'd bounced and bounced and then had been flung off before his neck vertebrae were severed were involved. Eventually, He took the cuts and coal dust to the grave.

It puts my thoughts on such things into an order of priority.

So I never became -an engineer

Regards

Norman

 

[Blogwitch]

Crowning is fairly easy to do. I have had to do it a few times.

I just set up around 1 degree on my topslide, then cut in from the edge of each side until you nearly meet in the middle. Then it is just a matter of gently rounding it over to form a nice curve using a fine file to begin with and ending up with fine emery.

It is the alignment of the two pullies that keep them on the crown, in fact, if you have the two pullies well aligned, the belt can be fairly slack and flopping about and still stay on. My early Myford had cone drive and it was dead easy to change speeds, in fact I think I should still have them knocking about somewhere after I converted it to a four sheave v-belt configuration.

When I remotored my old toolpost grinder after the 16,000 rpm original gave up the ghost and I had to fit a 12K rpm motor to it (the nearest I could obtain without remortgaging), because it used woven flat belts, I had to make a new pair of twin sheave pullies to retain the original output speeds to the spindle. They worked out great and have been that way for about 10 years without any trouble, so proving that coned pullies can take the speed as well, as this pic of internal grinding has the spindle at around 35K - 40K RPM, truing up the nose of a 5C collet chuck.

John

 

[Wizard69]

Really nice work on the pulley!

Leather is the traditional approach, usually laced together or sometimes glued.

If you aren't objectionable to modern materials there are belting systems that are blindingly simple and may work for a model. These systems are generally used in conveyors and the like. The stock material is cit to length and then melted together in a portable hot press. These guys: http://www.habasit.com/en/power-transmission-belts.htm have the conveyor belts, and a series of flat power transmission. The colors almost match your paint too.

These guys: http://www.durabelt.com/flatbeltinfo.php have flat belts in urethane. Interestingly they also have what the call crowning sleeves to slip on driver pulleys.

In the end there are many options out there. For a model I can imagine that looking good is a high priority so you may make decisions based on that. Your big problem is finding a local dealer if you don't want to buy over the net. You will need the belts made to order so you need to know the length and width.

 

[Tony Bird]

Hi,

Thank you for all the input. I will build a test rig to try out the different systems suggested. In a local hardware store I have bought some flat belts that are used on vacuum cleaners and the like and I have ordered some plastic strip to try out. I intend to check out my wife's selection of hand bags to!

I have so far made one pulley for the test rig. I will report results.

Regards Tony.

 

[goldstar31]

Am I stating the obvious. A lathe was-and in some instances called 'turns' or 'tour' in French. I learned on a watchmaker's turns when I was a youngster. The bodger's lathe still has its rope propelled by a pitman.

As for joining, my older ones were joined with metal clips and my little watchmaker's lathe is driven with a leather lace joined with a staple rather than a glued and sewn scarfed joint. Opinions vary about whether they cause ringing

 

[Herbiev]

Wives handbags are always a good choice for leather. And the contents for scrap metal Rof}

 

[Tony Bird]

Hi,

Made a third pulley this time with spokes.



A crown was created using a 'T' rest and graver.




The three pulleys made crowned?



Testing.



Video at:

www.youtube.com/embed/wzBJyiciLnY

Regards Tony.

 

[Tony Bird]

Hi,

At the model show last weekend I bought 2 foot of PMR 1/2" plastic belting. The belt was joined with super glue; the overlap of the belt being about 8 mm.

I made up a test rig for the pulleys made using some of the brass 'T' section used for the engine bearing supports on the large oscillator.





Video at.

www.youtube.com/embed/zR3cbP-Otvg

The belt worked well at both low and high speed; it is also available in 1/4" widths. I will continue to check out and check out other forms of flat belts.

Regards Tony.

 

[Tony Bird]

Hi,

Well it is the end of the week and I have managed to connect the pump to its eccentric. Also some rubber belt that was ordered on eBay has arrived. So I will put a copy of this missive in my thread on flat drive belts.

First the belt; having tried belts used in vacuum cleaners and belts supplied by PMR for use on their models the next to try is some 10 mm wide, 1 mm thick rubber belt. So far it is the cheapest of the products tried and cost £3.75 inc. delivery for about 2M. Like the PMR it is joined by overlapping it and gluing using Superglue and and both have the advantage over vacuum cleaner belts in that different lengths can be made up. As it is thicker than the PMR product the joint makes more of a slap when it goes over the pulleys. Unlike the PMR belt; being rubber the belt is slightly elastic which might be an advantage.

As the belt is bought.



The joint with the ends of the belt slightly chamfered. On joining the next belt I will try and make a longer chamfer.



So so far in checking out flat belts all seem to work well in that they stay on the pulleys and transmit power well. Next when I find some I check out leather and fabric belts.

Now the pump. Nothing different in the making of the components except perhaps using a shellac charged spigot to machine the outside of the small ends.




The finished pump mounted on the engine.





You've seen the pictures now watch the video of the belt and pump in action here.

www.youtube.com/embed/poRACkYbcpg

Make a bypass valve next I think.

Regards Tony.