Member postings for Pete Rimmer

Interesting chuck on that LeBlond. Seems to be a 3-jaw with both independent and scroll adjustment.

They did make a combination lathe apparently sold to the MOD a lot. There's an example documented here:

Combo machine

Edited By Pete Rimmer on 08/06/2019 18:36:05

An even simpler solution is to swap any two of the three phase wires to the motor. Then the default direction will be the direction you require.

I never heard of this. I don't deny that there might be some kind of aftermarket 'blipper' but I never heard of it and know of no factory bike that has the feature nor would I find it desirable.

For fast up-changes you can get quick-shifters, those are quite common but they simply kill the ignition momentarily - usually around 30ms - and I'm sure you can get some which cause a backfire when the change is done because I've followed bikes that backfired on every change though the one I had on my landspeed bike for a while didn't cause it.

There is unit designed for disabled bikers that power-shifts up and down, I don't know if perhaps that has a blipper function for the down-shifts. It's a large ungainly solenoid that most people would not put on their bike if they didn't have to.

The tool in the first post looks like it has been ground on a blunt wheel. If you're not dressing your wheel regularly you're missing out on the best of it's capabilities.

Comes the practice

Send me your address Philip and I'll post it on. You'll have to trim the length to suit.

Way oil, if I'm not using coolant oil.

It might not seem cheap but it does go a very long way. I doubt if I get through a litre a year.

Hobbing is the process of generating a tooth form by rolling a blank in time with a cutter having (normally) straight-sided teeth. The rolling action generates the involute profile, rather than the profile being ground into the cutter. The advantage is that only one cutter is required for a given tooth form. Disadvantage is the machine and hobs are expensive.

Here's a slow-motion video of a small gear hobber working:

Yes my hobber oil pump leaks from the stuffing gland so I keep a roses tin under the pump. As it fills up I pour it into a jug which I keep on the lathe with a brush in it. The sump was full of dark sulphurised cutting oil when I got it and I marvelled at how good the ways were for a 70 yr old machine, so I figured I would continue the tradition.

Sadly not. The profile-shifted gear must be hobbed, or else you must make a cutter to suit.

It makes perfect sense because I fired up Gearotic and generated a 14DP gear, added in some profile shift to bring the OD up to your 32.64mm which gives us a root diameter of 25.04. Your measurements of 32.64-7.4 = 25.24 is only 8 thou different from that so I guess it's fair to say that your gear is in fact a standard 15 tooth 14DP pinion, generated according to the long-addendum info in Machinery's Handbook.

Edited By Pete Rimmer on 01/06/2019 18:00:37

Edited By Pete Rimmer on 01/06/2019 18:02:21

Philip can you measure the distance across the bottom of the teeth i.e the root diameter? I realise you can't get the caliper jaws directly opposite with the odd tooth number but get it as close as you can.

I'm just an enthusiastic amateur so don't ever take my word as gospel, but I agree with Andrew. The long-addendum profile would be correctly generated if you were hobbing, but not if you are cutting with a single-tooth cutter since the shape is so far departed from the cutter's form. For a small pinion like that I'd grind a form tool from HSS and fly cut them I think, maybe gashing them out with a slitting saw first.

If I weren't so busy I'd have a go at hobbing a new pinion gear for you Philip.

The numbers don't stack up because of the low tooth count of the pinion. It's normal to increase the diameter of low count gears to prevent undercut and make the tooth stronger. According to Machinery's handbook (30th edition, page 2162, table 8) a 14DP 15 tooth pinion should be increased by 0.07569" (or 76 thou). If you subtract that 76 thou from the measured diameter of the pinion in question the numbers work out very close indeed for 14DP (14.06 actually).

The original Denford gears were made form a material called Technyl A90, whatever that is, probably a nylon as the name suggests. I have made quite a few replacements from Delrin.

I found that the original gear was rather mis-shapen on my lathe and it used to bind after it was worked hard and the heat caused it to swell. The delrin replacement never suffered any of this.

The original Denford gears were made form a material called Technyl A90, whatever that is, probably a nylon as the name suggests. I have made quite a few replacements from Delrin.

I think it is probably Boxford too. Boxford and Denford both used 18DP change gears but the Denford ones were 20pa.

How a person uses a VFD is a matter of preference of course but I find that one of the real benefits of being able to adjust the frequency is chip control. A small adjustment can mean the difference between stringy swarf birds-nesting around the chuck and little tiny curly chips making an easy to clean up pile in the chip tray.

I usually run them up to 100hz. As I see it, if you're running a 4-pole motor at double speed that's no different to running a 2-pole motor at normal speed, as far as the mechanicals are concerned.

Wall space is precious in a busy workshop IMO. Shelving and cupboards will store stuff on the wall that would otherwise be wasted space so I am firmly in the 'scrap the door and make a wall' camp. I don't have windows, just plenty of lighting. I have plenty of stuff in my workshop and all of it came through a single pedestrian door, albeit slightly wider than standard.

That's quite a valuable gear being similar pitch to Boxford. If you have no use for it then put it on eBay with a low start you might be pleasantly surprised at what it fetches.