View Full Version : Multi Chain Drive Drill Press Need Ratio Advice

Tundra Twin Track
06-07-2016, 01:05 AM
This is reduction drive on the IDL drill press conversion that I am working on.Low speed is 40to 80 rpm High is 150 to 300.It uses a variable spring loaded primary pulley and fixed secondary on 1740 motor.My goal is to speed it up by changing sprockets Ratio.

Small sprockets are 13T large 25T,Shafts CC is 3.870" No. 40 chain,was wondering which size sprocket would match up with shaft spacing 900 rpm high speed in my goal!
http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg1_zps2jawu4ze.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg1_zps2jawu4ze.jpg.html)



9http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg2_zpsjwmhu5vo.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg3_zps9b6avupo.jpg.html)d.jpgupo.jpg

Paul Alciatore
06-07-2016, 03:02 AM
It seems that you have a triple step down, each one of which has about a 1:2 ratio for a total reduction of about 7.11X. So your 1740 RPM motor speed is reduced to about 244 RPM. I am not sure how that fits into your two speed ranges: LO 40-80 and HI 150-300. Obviously there is another gear or chain step which allows the choice between the two ranges and some kind of variable control, electronic or mechanical.

OK, but you want to change the chain mechanism to get a higher final speed around 900 RPM.

Figuring the chain drive ratios is easy, but getting the spacing to come out the same is more involved and will take some work. Instead, how about just eliminating two of the three chain speed reductions. One reduction will give you a 1.9X speed reduction instead of the 7.11X reduction provided by three of them in series. That should make your HI range 555 to 1110 RPM. Your 900 RPM is in the middle of that range.

So just eliminate two of the chain reductions. The remaining one will use the same 13 and 25 tooth sprockets so the spacing will remain the same.

06-07-2016, 05:28 AM
Swap the driven and driver round?, haven't worked the numbers but it seems the right ball park, check it out though, I'm notoriously ****ty at mental arithmetic these days!

Tundra Twin Track
06-07-2016, 01:05 PM
It has quad drive,the 4th chain couples to quill sprocket shown in pic.The one sprocket has Sprague clutch that idles in high then when you turn knob above driven pulley it engages to use entire reduction.What I was seeking info for was the sprocket combo's that would work with that shaft CC spacing.I was shocked to see that many chains in there,it runs very quite I guess being submerged in oil does it.

http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg3_zps9b6avupo.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg3_zps9b6avupo.jpg.html)

http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg4_zpsjnjry99d.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg4_zpsjnjry99d.jpg.html)

http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg3_zpswmwd13xc.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg3_zpswmwd13xc.jpg.html)

06-07-2016, 02:07 PM
I think a Chain Length Calculator like this one https://www.rbracing-rsr.com/chainlength.html might be just what you need. Plug in your fixed numbers and then keep trying different sprocket tooth numbers until you get a chain link number that is "real world".

06-07-2016, 10:29 PM
There is a problem with links for two of the images in the OP. Seems
that their [/URL] [/IMG] info might have been truncated when other
links were pasted in.

Regarding the sprockets and chain. Given that changing sprockets
appears to require a bit of fabrication because of the hub details,
do you suppose that changing pitch might buy you any latitude?

ANSI 40 chain has 1/2" pitch and 5/16" rollers. Is this much chain
necessary for the application? Especially when running immersed
in an oil bath (and in a non-production environment.)

It may happen that you can get to where you want speeds to be
without this added consideration of pitch change. But if you can't
readily make the change using #40 chain ...

Incidently, the more you reveal of that machine, the more I like it.
Made in Canada, you say. Those WERE the good old days.


06-08-2016, 12:31 AM
So just eliminate two of the chain reductions. The remaining ones will use the same
13 and 25 tooth sprockets so the spacing will remain the same.I see merit in this thinking.

The middle two chain sets are driven by pairs of 13T-25T sprockets fixed
together on a sleeve with a bush inside so they can freewheel on their
respective shafts, yes?

As Mr Alciatore suggests, cut out the middle-men. Maybe add a keyway.
Maybe add a dummy sleeve(s) that goes in place of the middle sprocket
pairs and drives directly down from top chain set to bottom chain set?

Something simple, reversable and which retains the two-speed feature
without introducing any tooth count, CC distance, pitch change or other
headaches ought to announce itself to you after due time spent pondering.

Incidently, is there some kind of breather system for the compartment?
When thinking about consequences of doubling the speed of the four-chain
layout, I wondered about windage. If eliminating two chain sets proves
workable, I suspect windage might even be reduced compared to stock.


Tundra Twin Track
06-08-2016, 02:09 AM
Thank guys I will look to see if that idea Paul has would work,Arcane link for chain length & ratio very handy.The oil that came out of it is not gear oil any suggestion for type,no breather on it Eddy.

It pretty cool to see Renolds chain made in England and Renolds sprockets made in Canada.All sprocket like new condition,roll pin that sprague clutch engages need replacing.Is there a specific oil used when running sprague clutch,my lathe one on apron for rapid travel.

Ya Eddy my photo bucket was not happy earlier,operator error lol!

06-08-2016, 03:06 AM
Do you really need 900? A motor swap would put you in the 600 range.

06-08-2016, 05:28 AM
I suppose you are aware that it's good to have sprockets and number of chain links without a common divisor so the same chain links don't always run on the same teeth. At least in theory.

06-08-2016, 11:00 AM
The oil that came out of it is not gear oil - any suggestion for type, ....I do not have a brand/wgt to offer, but can suggest some principals to consider.

A non-detergent oil that allows debris to settle, not remain in suspension
A weight (& additive package) that discourages aeration - frothy oil is a poor lubricant

In this link to an article in MachineDesign, there is a chart that suggests
selecting SAE 20W for RS50-or-smaller chain operating in a Type B lubrication
environment (bath/slinger discs) at ambient temps of 32-104F. (An equivalent
to SAE 20W is ISO 68.)

"Getting More Life From Roller Chain" (http://machinedesign.com/mechanical-drives/getting-more-life-roller-chain)
By Michael Hogan
Machine Design 2011.05.01

I believe author Hogan's oil bath scenario is a situation where the chain's elliptical
path is on a vertical plane with the chain dipping into oil at bottom, whereas
TTT's is horizontal with the chains fully submerged. Notice Hogan's caution
about oil heating when chains dip down too deep - extrapolate to TTT's
configuration with four chains entirely in the oil bath.

Thoughts here about aeration stems from past experience with pressure-fed
plain bearings in motorsport - maybe frothy oil is less an issue for submerged

A mitigating factor is duty cycle - presumably short in TTT's case, so heat
& froth are perhaps of no consequence.

Tsubaki, Reynold and other chain mfrs have lots of design/maintenance info
available on line.


Tundra Twin Track
06-08-2016, 10:06 PM
Yes Paul you nailed it,I will not run the bottom 2 chains and will run a 13 tooth sprocket with chain coupler or build a fingered coupling to engage sprocket.Pressed 25T sprocket off pretty tight Greenerd got it done,just about had to go to the big Dake.Thanks again it was sitting right in front and did not see it!

http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg1_zpsae03hgk2.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg1_zpsae03hgk2.jpg.html)

http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg2_zpsuz9ogbdk.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg2_zpsuz9ogbdk.jpg.html)

http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg3_zpsovgemegr.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg3_zpsovgemegr.jpg.html)

http://i1371.photobucket.com/albums/ag292/tundratwintrack/image.jpg4_zpscj6rod8b.jpg (http://s1371.photobucket.com/user/tundratwintrack/media/image.jpg4_zpscj6rod8b.jpg.html)

Paul Alciatore
06-09-2016, 02:05 AM
Glad it worked.