Gears are gears right?

[John Rudd]

I'm looking into the feasibilty of making my own sheet metal rollers....Nothing too ambitious about 12in across..

To make the lower pair of rollers turn simultaneously, they are generally gear driven...

So, can I make use of any spur gear  or is there some difference depending on application?

Was thinking along the lines of using two 30t spurs gears for the ML7 ( cheaper than buying a cutter and messing about...)

What do you all think?

[John Stevenson]

Absolutely no reason why not. probably your biggest design feature is the centre distance between the two gears.

If you are using Myford gears which as 20 DP then the centre distance of two equal number gears is the pitch circle diameter which is worked out by taking the number of teeth and dividing by the DP so for 30T gears the rollers need to be 1.5" apart.

John S.

[John Rudd]

John,

Thanks for the reply...

As it happens I have 2 such gears from my 9*20 lathe, so I think they have become suitably employed, as I dont do a lot of scew cutting in my lathe......

[andyf]

Here's a source of reasonably cheap metric module gears: http://www.technobotsonline.com/gears.html .The mod 1.25 ones are roughly the same sort of size as Myford gears, and the teeth are 15mm wide, which might be a good thing. Where T is the tooth count, the PCD of a mod 1.25 gear is 1.25 x T mm, so two 30T gears would have a centre distance of 37.5mm. which is only 0.6mm less than their 20DP equivalents. 

Andy

[75Plus]

Here's the fly in the ointment.  Using two gears will turn the rolls in opposite directions. A third one will be needed to correct this. Two small sprockets and a bit of roller chain will achieve the desired results. You can also use sprockets and chain to connect the adjusting screws for the movable roller.

Joe

[John Rudd]

Andy,

Thanks for the link

 I keep forgetting about Technobots selling stuff like that..( I bought some caps from them not so long back too.... )

Their prices arent too bad except I can get a pair of gears from RDG cheaper if I had to spend...( tight northern monkey..      )

As luck would have it, I have two 30 tooth gears from my lathe that will do nicely.....


Oh, Joe.....

I guess I ought to have known better that it wouldnt be easy.. (grrr...)

I guess I'm going to have a rethink on this..

I can get a 12 in roller for £100 or can buy a kit from Hemingway kits for £107 plus carr but that is only 10 inch wide...or I can pursue my dream and build one for less....that would be 12 inch across...

Choice, choices  choices......

[75Plus]

John, I looked further and found some examples that used two gears. The material was fed through the geared rollers onto the movable roller. That scheme would require that the driven rollers would need to be adjustable for various thickness material.

I recently constructed a 4" wide roll using two #25 (1/4" pitch) sprockets. I have emailed you a few photos of that effort which may be of interest.

Joe

[John Rudd]

Joe,

Top man....

I'll take a look adn see what's what.. Many thanks 

[Bogstandard]

John,

A few years ago there were plans knocking about that didn't use gears, but a pair of cranks, with a conrod between them. Maybe someone else has come across them and know where to get the plans from.


John

[John Hill]

John,

A few years ago there were plans knocking about that didn't use gears, but a pair of cranks, with a conrod between them. Maybe someone else has come across them and know where to get the plans from.


John

Aha!  That remindes me!  I think the 4 1/2 litrer Bentley of Le Mans fame used connecting rods and eccentrics to drive the overhead cam shaft?  Anyway, eccentrics might be easier to make than cranks.

[Bluechip]

The NSU Max used that, or a similar principle.

Pic of bike, no detail ..

http://classic-motorbikes.net/gallery~nsu-classic-motorcycles

Dave BC

[John Rudd]

Chaps,

After considering the pros and cons, I decided to just buy....

Got a set of rolls from fleabay for £90 delivered....(I posted up on HMEM, but cant access the ste right now...)

My biggest problem would have been drilling the roller ends in my lathe....but looking at the rollers I dont think I would have needed to.....

Never mind....