Member postings for Andy_H

Ah, I entirely see your point and of course the unintentional ambiguity in my post. Apologies.

So, the lathe (a Flexispeed) is 12" between centres. The part I want to replace (the mandrel) is about 5" long and would be produced from 0.75" diameter steel.

I would, of course, expect to produce a proper drawing. But I think another point I perhaps failed to explain in my original posting was I am not ready with all the precise details yet (I am working on that) but was instead simply trying to gague whether this is it's the sort of thing that would be deemed acceptable to seek help with or, to be put it bluntly, be looked upon as a damned cheek!

Andy

I hope if put this post in the right place - it seems the most appropriate forum to me.

I need a replacement component made for an old small (12"  lathe. It's a new mandrel with a different nose thread). So it's a small component but includes a small section of screw cutting and internal morse taper, which I am unable to do with the facilities (and expertise) I have.

I'm looking for some advice on whether there is an "accepted" (or recommended) way of finding out if it's the sort of thing someone would be prepared to help with. Or, indeed whether it's a job that's too big (in complexity rather than size terms!) to expect help with.

I'm also going to do a bit of googling to see if I come up with any suitable commercial services that aren't prohibitively expensive but thought it would be worth asking here as well.

Andy

Edited By Andy_H on 13/09/2023 16:33:13

Thanks for all the replies on this.

I think I'm down to two options. 1) the brushed motor kit in my earlier post or 2) the Jack servo motor Clive pointed me towards. As I currently see it both have their different advantages and "disadvantages"..

I like the relative simplicity of the brushed motor kit coupled with the relatively simple and easily replaced electronics should that unit fail. On the other hand, the maximum speed (since the lathe shouldn't be run above 1000 rpm) needs to be controlled by pulley selection and/or a position limiter on the potentiometer. The fact that torque is reported to be good down to around 400rpm suggests the optimum set-up might be to arrange pulleys so as to achieve minimum lathe speed at a motor speed to 400rpm.

On the other hand I like the Jack (or similar) servo motor option as I believe these can be programmed to limit maximum speed, which eliminates the need to implement something separate to prevent speed being set too high for the lathe. Also, as I understand it, the exact required speed is achieved by programming (setting) the required speed rather than having to calibrate positions on a potentiometer dial. But, the electronics are far more complex/specific to the motor so if they fail (maybe rare occurrence I know) one is probably more reliant on the original supplier.

Richard B - particularly interested in your reply as I was scouring the Internet yesterday afternoon looking for alternatives to the brushed speed controller provided in that kit and, coincidentally, the one I homed-in on was the unit you are using (with delivery from UK stock). So, it's good to find someone that has used that. Reason I was looking for an alternative to the supplied unit was: 1) because of the 100Hz noise problem Peter Cook mentioned and 2) I wasn't convinced it looked sufficiently robust. Does your unit eliminate the 100Hz spike problem. Also, does it dissipate a lot of heat - I wondering if it would be cope with being enclosed or whether it needs free air-flow all round?

So, as always there are choices! I've not yet decided but currently slightly favouring the brushed motor kit (with later replacement of the controller).

But, in the short term, a moment of common sense struck over the weekend. As this project is restoration of a newly acquired lathe which I have never used it occurred to me it was probably sensible to get it set-up with the original hefty motor and counter shaft to confirm there's no issues with the lathes before I spend money on a replacement motor! It will only be a very temporary lash-up (very literally) to get the lathe spinning - started over the weekend but a bit more to do.

Andy

So the evidence points to an intermittent problem and maybe that the switch is sticking.

My approach would be to disassemble the motor and check the centrifugal switch is sliding freely on the rotor shaft and clean/lubircate if necessary.

Andy

Is this the sort of thing Link you are referring to?

Another option I came across in my hours of searching ebay is this brushed DC motor package. I wonder if anyone has any thought, or indeed experience, of this offering?

BTW, I considered all the suggestion made by those that have replied to my threads on these matters. I originally dismissed the advice to go down this route due to my preference to keep the whole setup sort of representative of its origin (countershaft and all). But I also one of my key objectives is to make this whole setup as compact as possible and easily stored/moved. What I've come to realise in the past week or so is these two aims aren't compatible and with compactness being my main objective I am now eating humble pie and changing my mind!

Andy

Out of interest what did you use as a power source in that setup?

Andy

I know it will be a pain chasing it (especially if certain parties fail to respond) but the fact you have a PoD photo showing a property that is not yours puts you in a stronger position than is often the case in these circumstances - just don't go painting your front door any time soon

But, the way I would handle this is to message the seller and then if not resolved raised a case on ebay. I've had to do this in the past and got a refund - albeit the process takes (from memory) about 10 days.

Andy

You probably only get one chance in the real thing as well - just be grateful you were in a simulator

Andy

I think PS is probably more common but, according to Wikipedia:

Metric Horsepower: hp(M) – also PS, KM, cv, hk, pk, ks or ch

Andy

I think I've worked it out.

I believe the "M" denotes metric horsepower.

That's the units sussed. As for the value I conclude it must be 0.25 but with the decimal point missing.

The quoted voltage and current product is 122W which implies about 66% efficiency.

Andy

I agree.

And my thought about being notation for 0.025HP doesn't stack up either!

Andy

This is the label. Not sure it really helps - there's no manufacturer and the model no does not yield anything on Google.

I'm wondering if it's an odd decimal notation that signifies 0.025 HP - which would be ~18W

Andy

I've been looking at an electric motor. In the HP section of the motor plate it says "25M" (yes, it is "M" and not "W".

Any idea what that really means?

Andy

I take that back! Thanks, that link gives a good explanation of the hardness numbers that had previously mystified me.

Andy

That looked like an interesting suggestion but having looked into more detail it seems these are all made of plastic materials and I am thinking this would not provide the required degree of friction for driving the countershaft wheel.

My current idea is to use one of the larger and "chunkier" Rubber ferrules for a walking stick which has a solid parallel sided Rubber section on the end. Unfortunately the diameter of that section is 15mm less than I really wanted but can compensate for that by adjusting the diameter of the countershaft wheel.

Andy

That's a good idea.

Looks like this may be perfect as it's 50mm diameter, and also straight sided rather than conical. I'd have to remove some material from the centre to fir the boss on the shaft.

I'm guessing rubber is not very machinable (more of a hole-saw job) - or am I wrong?

Andy

Thanks for the suggestion. My badly worded question was aimed at the rubber covering on the motor disc. The inner tube slice is an interesting idea but I'm wondering if that would be think enough and robust enough. But the idea has led me to look at large bore reinforced rubber hose.

Also, for the wooden boss on the motor shaft I'm thinking of boring that out and gluing a couple of shaft collars into the hole. Thinking this may be a more secure (safe) way of fixing to the shaft rather than relying on a screw through the wood - which could result in the wood splitting when under load?

As for the countershaft side of things. I am now thinking of using two rings bolted together with the pulley sandwiched between them. This would avoid ruining the original pulley buy drilling holes through the rim.

Main hesitation still is whether the whole setup would be effective so would still be interested to hear if anyone has used this method

Andy

This 2015 thread drew my attention to the wonderfully neat "lathe in a box" Link

The part of this solution I am particularly interested in is the belt-less method used for the motor to drive the countershaft.

Curious if anyone has experience of using a setup like this and if so how eefective you find it.

The photos in the above link are quite small and not too clear when zoomed but....

It looks like a plywood ring has been screwed to the outer surface of the original drive pulley. That seems very easy to fabricate but I reckon it needs to be truly concentric to the pulley and with a even internal surface to avoid inducing annoying vibration.

I'm less clear on the motor drive side of this setup. Looks like a rubber wrapped brass boss attached to the motor shaft - a bit like a over-sized version of pinch roller found in cassette players! Any suggestions on how to make this (assuming such a component is not available?) or, more to the point, what to use?

Andy

Index, and HP RMB (Rocky Mountain Basic) was a wonderful environment for creating instrument control and analysis applications. Wrote many many thousands of lines in that. For example, producing software that had a 6 metre parabolic microwave antenna whizzing round whilst collecting receive data and generating contour plots was great fun.

Andy

Maybe not very helpful but my view on this is....

Yes, "things" (generally) aren't built as big/heavy as they used to be. But equally materials and manufacturing technology have moved moved on significantly. So smaller/lighter can't always be taken as an indicator or poorer quality or poorer performance.

I'd suggest that (for the same rated HP) key consideration between bigger/smaller, new/old is comparison of the specification of the two units.

Andy