Speed change Warco Economy Mill

[Speedy Builder5Participant @speedybuilder5]

making life easier

[Speedy Builder5Participant @speedybuilder5]

If you have a mill/drill where there are 2 'V' belts to change to get the right speed, You know what its like, you seem to have to take the upper belt off, then the second belt so that you can select the right speed.

My belts were a bit tired anyway, so I have bought 1 x motor to intermediate pulley and 2 x intermediate pulley to spindle. Ie I have a belt either side of the motor belt (Does this make sense ??) which can be used, but not at the same time.

=====================

Motor==========I/Pulley SPINDLEpulley

Pulley ======================

Now – why do I do this – Simples (Merecat language). The upper belt can be used for a motor /intermediate pulley combination without removing the motor belt and the lower belt left in the guard tray, and the lower belt taken off the tray for those combinations of pulleys below the motor /intermediate (The upper belt having been taken off completely).

It may have made more sense to have 2x motor belts as the motor tension is simple to change anyway. But that was an afterthought.

Bob

[RobboParticipant @robbo]

Good idea Bob, and cheap. Used to have a mill/drill, and as you say the belts were a pain to change.

Phil

[Speedy Builder5Participant @speedybuilder5]

I have been scratching the grey matter – again! I have a cunning plan, If I add 2 additional pulleys one each on top of the motor and the other on top of the intermediate pulley (centre pulley), I can get most of the available speeds without having to totally remove the final drive belt. Owners of these mills (without VMC drives etc) curse at the awkward way of changing from low speed to high speed ranges.

I think that I can find a way of adding the new pulleys (famous last words), but can others see a problem. The attached diagram shows the new pulley set as ——– 8 ——-. I havn't worked out what speed ratio 4 – 8 will give me, but may work that out tomorrow when next in the workshop.

[Speedy Builder5Participant @speedybuilder5]

Using ENGINEERING TOOLBOX formulas:-

Pulley speeds and sizes

Single Belt Transmission – one driving pulley and one driven pulley

For a system with two shafts and two pulleys – as indicated with pulley 1 and 2 in the figure above:

_{d1 n1= d2 n2 (1)}

where

d₁ = driving pulley diameter (inch, mm)

n₁ = revolutions of driving pulley (rpm – rounds per minute)

d₂ = driven pulley diameter (inch, mm)

n₂ = revolutions of driven pulley (rpm – rounds per minute)

Equation (1) can be transformed to express the

Revolution of Driven Pulley

n₂ = d₁ n₁ / d₂ (2)

Revolution of Driver Pulley

n₁ = d₂ n₂ / d₁ (3)

Diameter of Driven Pulley

d₂ = d₁ n₁ / n₂ (4)

Diameter of Driver Pulley

d₁ = d₂ n₂ / n₁ (5)

Multiple Belt Transmission Systems

For a system a with three shafts and four pulleys – as indicated in the figure above:

n₂ = n₃ (6)

n₄ = n₁ (d₁ d₃) / (d₂ d₄) (7)

Example – Multiple Belt Transmission System

The revolutions of shaft 4 in a multiple belt transmission like indicated in the figure above where

n₁ = 1000 rpm

d₁ = 100 mm

d₂ = 50 mm

d₃ = 110 mm

d₄ = 60 mm

can be calculated as

n₄ =(1000 rpm) (100 mm) (110 mm) / ((50 mm) (60 mm))

= 3667 rpm

For the Warco Economy mill with pulley mods – see next page

[Speedy Builder5Participant @speedybuilder5]

 

D1 is the motor pulley, D2/D3 are the intermediate pulley and D4 is the spindle.  Adding a 5" pulley on top of the motor pulley and a 2.25 into the top of the intermediate pulley. The following changes could be made without totally removing any belts, just moving up and down.

D1     D2       D3      D4 N1 N4           Belt #
2.0	5.25	2.25	6.875	1440	180	“4/5
2.0	5.25	3.375	6.0	1440	309	“3/5
2.25	6.875	3.0	4.375	1440	323	“4/6
2.0	5.25	4.375	5.125	1440	468	“2/5
3.375	6.0	3.0	4.375	1440	555	“3/6
4.0	3.375	2.25	6.875	1440	559	“4/7
2.0	5.25	5.25	4.25	1440	678	“1/5
3.0	4.375	4.375	5.125	1440	843	“2/6
4.0	3.375	3.375	6.0	1440	960	“3/7
5.0	2.25	2.25	6.875	1440	1047	“4/8
5.0	2.25	2.25	6.875	1440	1047	“4/8
5.0	2.25	5.25	4.25	1440	1440	“1/8
5.0	2.25	3.375	6.0	1440	1800	“3/8
5.0	2.25	4.375	5.125	1440	2732	“2/8

Edited By Speedy Builder5 on 04/08/2020 14:47:24

[Speedy Builder5Participant @speedybuilder5]

Bit the bullet the other day after a hectic week of belt changing, picked up a piece of Al at the metal recycling yard – probably a roller off a conveyor belt – scrap price 4euro/kg Made up 2 new pulleys and attached them to the motor and intermediate pulley – Happy lad now.

[not done it yetParticipant @notdoneityet]

Scrap price

I wish I could get £3.50/kg for scrap Aluminium! About ten times the scrap value!! More like 4kg/ €?

[MeunierParticipant @meunier]

Speedy5 is in the (French) ball-park.
A slab of markedly second-hand ali complete with a couple of holes, approx 300x200x40mm out of the local metal distributor scrap bin was 3€/Kg late last year. 4kg=12€
DaveD

[Author]

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