pulley dims for boxford csb

[onecut]

Hi,can anyone help me with a problem l have l,v just been informed the pulley on my csb is not correct.l need to make another which is the easy bit ,the hard bit is l dont know dimensions of the correct pulley does anyone have the information l am after-thanks(one cut)

[jonnydeen]

the following is from Boxford CSB Lathe (http://www.lathes.co.uk/boxford/page11.html)

"the CSB was delivered complete, ready-to-run with a 1/3 h.p. motor for £105 - a total saving of some £16 : 5s : 0d. The simplified 8-speed drive had the motor bolted direct to the countershaft upright instead of on a separate, adjustable horizontal motor platform. With a single-pulley drive on motor and countershaft, and using backgear, the eight spindle speeds were: 38, 55, 87, 125, 200, 285, 450 and 650 r.p.m. By paying £3 : 10s : 0d extra the motor and countershaft could be fitted with 2-step pulleys when the speeds became: 38, 55, 75, 87, 110, 125, 175, 200, 250, 285, 400, 450, 570, 650, 900 and 1300 r.p.m. Unfortunately the makers neglected to mention the fact that in order to run on top speed a more powerful and expensive motor was required"

now you know what speeds you should have, you should be able to work out the pulley diameters needed

[BillTodd]

Brian, I looked at my brothers AUD to day but it appears to have a different (modified) drive system :(

As jonnydeen says, the simplest way is to work it out backwards
i.e. if the spindle is to run at 1300rpm at its highest speed, then work out the ratio of diameters of the small spindle pulley and the large intermediate pulley

These are probably in to order of 80 and 120 so ratio is 4:3 which means the intermediate shaft will rotate at 3/4 of the speed of the spindle = ~1000rpm your motor does 2800rpm so you need a larger motor pulley (1000/2800) about a third of the size of the smaller high speed intermediate pulley.


The fastest slow speed quoted above is 450rpm 3/4 of that is ~337rpm so the small motor pulley has to be 337/2800 = ~8.3 times smaller than the slow speed intermediate pulley (In the picture it looks to be about 250mm diameter the motor pulley will be in the order of 30 mm which is a very small pulley for an A section belt! )

If you let us have the actual dims we can work it out for you.

[onecut]

Thanks bill,l worked it out and its impossible the big pulley on top is 8.4 l think bottom one is 1/4 size top one laurent send me a photo image of both, scaled them thats how l come to the 1/4 size.So with that bottom one would be 2.1ins l wanted to half speed of my motor so half that pulley size 1.05 these sizes are tho o/d of the pulleys so the depth of "v" is approx1/2in each side take that away and you have a heap of alluminium cuttings and no bottom pulley if l reduced top 2, new belt. Object was to save money so its going l,m getting one l should have bought 1400 rev,sell the 2800 one its a nice little motor so should go no bother-thanks for your intrest-one cut

[BillTodd]

Brian,

Why not look for a 2nd hand 3ph motor and A VFD. It might cost you an extra few quid but you'll only need one pulley and also gain infinite vary speed, slow start, quiet & smoother running, simple reverse (for threading with half-nut closed) etc. etc.


Bill

[onecut]

hi bill, yes l,v been told this what sort of money are we talking about?l know you have build many machines in your time so excuse my ignorance,but what about an industrail sewing machine motor, be honest the one that came with my lathe l,m pretty sure is one.lm throwing it out as nobody is able to work the wiring out.By looking on ebay these motors are clutch operated push handle down stops pulley-pull up allows pulley to revolve, bit like a brake or emergency stop.theres a 3pin socket on motor guessing this is for the foot pedal,when you plug a sewing m/c in doesn,t start its only when you plug foot control into m/c put pressure on starts motor ,more pressure applied faster it goes,so l know l must be missing something here but is that not a variable speed control.If wiring was changed to increase/decrease via knob why would this not work and why are these motors so cheap one on gumtree brand new one £20 the one l.m throwing out hums then when you kick start the pulley starts. l think it would work if l got a 3pin foot conrol thats why it wont start on its own but l want a new smaller one so its going -excuse the grammer(one cut)