Round belt and flat belt ecological niche and where to get them?

[PekkaNF]

I need two different belt drives.

One about 200w and 4000 rpm OD grider, motor and stone pretty close the same speed.

The other for ID grinding and pretty sure I need max I can get (min. pulley diameter)

I never used before round belts, but there are a lot examples on YouTube and books that indicate it is doable.

I failed to find a (metric) calculator that heps me to guestimate will it work or not? Is there any good rule of thumb e.g. 5 mm diameter modern urethane beltting?

Is there any magical number, after round belt is great vs. V-belt or is not viable any more?

Where to buy the belt and are there some standard endless rings or do I need weld my own?

Another choice would be a flat belt, but I have completely failed to find any source that would cater private customers for 1-3 belts.

Reason I'm asking that I had some FD-Z (5 mm wide V-belt, ribbed) and I tough I could use it on this one too, but can't locate any new anymore. Maybe small V-belts are as obsolote I am?

Than you.

Pekka

[Arnak]

Hi,

The first thing is that the belt required is the type of pulley that you are using.

Flat, A section, B section etc?

Then use a belt calculator to find the length you need:-

http://www.durabelt.com/beltlengthcalculator.php

This page has the angles for the groove and the width of the belt so you can see which type you require :-

http://www.globalspec.com/SpecSearch/SearchForm/motion_controls/power_transmission_mechanical/v_belt_pulleys

A flat belt uses a rounded top pulley so you would know if you need that type.

Belts are available in all sizes and types, just try a google search when you know what you require.

Martin

[PekkaNF]

Thanks, but this is for DIY spindle and pulleys I can make if I got the right belt.

Normal V-belts I can locate are way too wide (like 9 mm or more SPZ is 10 mm etc). Those would rob best part of the torque available. On these rpms even 5 mm wide would do nicely.

I would very much like to try flat belts, I know they need a crown on wheel and I have some equipment with about 2" wide flat belt, but I can't locate small continuous flatbelt.

I also don't have any real experience on round belt. I can find some figures on how high velocity can be and a lot of anecdotal indication that 5 mm might be the ticket.

I used this to guestimate:
http://www.durabelt.com/crosssectioncalcinfo.php

However, I would like to use miniature flat belt, because I need to learn that eventually anyway. I can't use cogged belt on ID grinding spindle, due to vibration and I don't like whining a toothbelt would do on that rpm. Unless I have no other choise.

This thread was interesting, he wants even a hihgher speed, but got basically the same problem:
http://www.cnczone.com/forums/linear-and-rotary-motion/77656-high-speed-belts.html

Pekka

[chipenter]

Check out polly v belts I used one on my toolpost grinder , bought a 6 row j size and split it down the middle , the pullys are not hard to make and the smallest pully is 20mm dia .

[velocette]

Hi PekkaNF
Have you considered using "Poly Vee" belts using  possibly 3 ribs with your 400 watts power at 4000 RPM
Pulleys are easy to fabricate in cast iron or aluminum.
Large differences  in diameters of pulleys are possible compared to Vee Belts 

Eric

[philf]

Check out polly v belts I used one on my toolpost grinder , bought a 6 row j size and split it down the middle , the pullys are not hard to make and the smallest pully is 20mm dia .

I used round belts (not sure if they're 5 or 6mm dia. - I'll check) for my toolpost grinder but I only use a 90w motor.

I use Poly-V's on several machines and as chipenter says you can go down to a 20mm dia. pulley with a J-section belt. Belts are very easy to get particularly if you use one from e.g a lawnmower.

Groove dimensions and power graphs:





Phil.

[velocette]

Hi PekkaNF
Whoops this got missed on previous posting a bit more info on "Poly Vee Belts"

[SwarfnStuff]

Hi Pekka,
    If you do use the round belt I'm fairly sure the 5mm urethane one uses a small double barb joiner. At least what I used on my X2 mill belt conversion does. The joiner is like a super small barbed hose joiner and fits down the hollow centre of the belt. I started with the green welded one but kept breaking the weld even when I got the shop to join it for me as the small pulley was 20mm diameter.
  If I were to do it again I would opt for the poly vee and buy twice the width so it could be split and I would finish up with a spare and save postage. (Scrooge)

[PekkaNF]

Thank you.

Sooo....

Studio audience greatly agrees that I should have a look on Poly-V (multirib) belts and they will eat the lunch of round belt and flat belt any day.

Smallest I got from local auto store was 3PK 560, I'm twiating it in my hands and it feels like it would transmit few kW at 3000 rpm. I.E. pretty stiff. Therefore I'll be looking PJ section, judging from the graph you kindly provided PJ section looks pretty good bet. I have seen on home applience small polyVs on incredibly small pulleys, just turned at the end of the motor shaft and then flat cylinder, pretty much like flat belt pulley sans crown.

So, it looks like that pulley section is not overly critical. I read some Stevenson's writing on using thread chaser of nonstandard angle and still working. I can grind HSS to that accuracy on single point tool. PDF even had rounding and some toleraces.

Still somewhat interested on round belt. I just got a small DC motor 70V DC 1,8A 30Ncm 110W 4500 1/min that might be better suited to round belt.

Pekka

[Swarfing]

I used a chaser on JS's recommendation to make some pulleys for one of my mills a good while ago. This worked a treat for my 5 rib belt, make sure you use coolant though as the ali will gum up quickly on those small threads. Don't quote me but i think I used an 11/16th thread cutter which worked out for the metric belt used. The belt will just bed to the cut grooves anyway.

[PekkaNF]

Poly-V and PJ-section seems to go under very many names, but I found this site:
http://www.best-drive-belt.co.uk/index.html

and ordered two three rib PJ-section poly-V belt and two 10 mm wide flat belts. Flat belts should be interesting, they should allow 12 mm small pulley and over 30000 rpm and still transmit 0,4 kW no problem. Have to consider centre distance.

I have no first hand experience on small fast flat belt drive. On my milling machine there is about 2" wide, just under 1/4" thick modern spiced belt for slow 3-5 kW motor and about metre centre distance. Crown on the wheels is very small. On grinder there are bits and bobs of ID grinder attachement and smaller wheels have a really pronounced crown. They look pratically like 1" dia miniature old whiskey barrels. I would imagine that modern low strech wheels will need a very small crown if properly lined up. Any opinion this one?


Belt calculators there were very professional lookking and easy to use. They even calculate belt tension and equivialent resonance frequency.

Now I have to find a way measuring 60-100 Hz frequency trough microphone.

Postage was whopping 29€ euros, they probably don't like to get european customers. But because they had multirib, flat nad round belt AND they had a very nice calculator I desided to give them a try.

Pekka

[philf]

Poly-V and PJ-section seems to go under very many names, but I found this site:
http://www.best-drive-belt.co.uk/index.html

Postage was whopping 29€ euros, they probably don't like to get european customers.

Pekka

Pekka,

They're in Austria so already in Europe.

A nice calculator. I checked my CNC drive on it (5 rib J section; 90 & 45mm pulleys; 5,000 rpm motor; 10,000 rpm spindle) and it looks to be OK to 6.5KW!!! My motor is around 550W at 3,000rpm so the belts should just about be OK. 

When I put my slowest pulley combination in (33 & 100mm) and put an input speed of 1,000 rpm I'm still OK with a huge safety factor at 0.6KW total (120W per rib). (I guess at 1,000 rpm my motor is only around 200W.)
The calculator only allows you to select standard pulleys unfortunately.

Phil.

[vtsteam]

Now I have to find a way measuring 60-100 Hz frequency trough microphone.

Try Visual Analyzer -- it's free to download. I've often used it to analyze the frequency of an engine from  video playing on the computer. If your camera can take video, just record your source, and analyze the audio playback on your computer via capture of the output and pipe it to the analyzer.

It works with other people's videos, too. Find an engine on youtube and want to know how many RPM it is running? Check it with VA. 

Visual Analyzer:

http://www.sillanumsoft.org/

[Sea.dog]

Pekka, Here are a couple of links to suppliers in the UK that do flat belts.

http://www.beltingonline.com/flat-endless-belts-13049

http://www.best-drive-belt.co.uk/flat-belt/flat-belt.PU11.html

Regards

Graham

[PekkaNF]

Poly-V and PJ-section seems to go under very many names, but I found this site:
http://www.best-drive-belt.co.uk/index.html

Postage was whopping 29€ euros, they probably don't like to get european customers.

Pekka

Pekka,

They're in Austria so already in Europe.....
Phil.

My bad! I jumped into conclusions here: http://www.best-drive-belt.co.uk/

VT, I'll have to chek that Visual Analyzer, nice hint.

THANKS  for all the responses. Now I have to visit my parents to help on some roof insulation before I return back home and hopefully have the belts waiting for me.

I'll try to grind HSS to 40 degree form tool for J-section pulley. This site did not have those pulleys on stock. Anyway, I probably need to play a little with ratio.

Pekka

[tom osselton]

Whenever we needed a belt Dad gave it to us!!!