Flexispeed Mk 2 – Size of Gear on Leadscrew for power feed

[Andy_HParticipant @andy_h]

I thought I had come across a post on this topic in the past but, if I have cannot find it again so….

The gear on the end of the leadscrew of my Flexispeed Mk 2 has some badly worn teeth, to the point that will now only engage with the worm and power drive the saddle for about half a turn of the leadscrew. It wasn’t in great condition when I got the lathe but has worn more by, I think, the mechanism slipping out of the locked position whilst in use. It’s not obvious to me the reason for (in my view) such a poor choice of material for these two small gear wheels!

So that leads me to the job of replacing that small gear. I originally thought of making one by had: using a dividing plate to mark the centres between teeth around the circumference of a bar, using a piercing saw to cut down to the bottom of those centres and then forming the teeth with a needle file. But I’ve had second thoughts.

Although “in my world” (that is, clocks) I would call this a pinion a bit of googling suggests the correct term may be a spur gear?

A couple more hours of googling suggests I can probably buy something suitable If I know what I need!

It’s a 10 tooth wheel and I can obviously measures outside diameter (0.5″ before the wear I reckon) and the thickness (about 5mm). But I get stuck when it comes to the tooth specification eg. MOD.

Can anyone help me by providing the correct spec of the part I need to find?

Andy

[JasonBModerator @jasonb]

Most likely an imperial gear,  the calculation is (No of teeth +2) /DP so 10 +2 / DP =0.5 therefore DP =24.

The only proviso is that some of the smaller tooth count gears can be slightly modified so you may find the gear is a bit more than 1/2″ OD

Next question is pressure angle, given the age of the machine I would say 14.5deg which makes it a bit harder to find off the shelf as most these days are 20deg pa.

Width will probably be wider but you can face that down and also alter the bore if needed

You need to look for a 10T 24DP 14.5pa gear.

[BazyleParticipant @bazyle]

But doesn’t it mate with the worm? You might need to make a worm to match the one on the layshaft and then make it into a hob……..

[bernard towersParticipant @bernardtowers37738]

Looks awfully like worm and wheel when looking at lathes.co.uk

[JasonBModerator @jasonb]

The only image that I could see of what I think are the Mk2s is the second from last and it looks like a straight cut gear and could be why the description has worm & wheel in inverted commas. Other models is is definately cut on the angle to suit the worm so it may just be the camera angle on the Mk2 making it look straight.

 

[Michael GilliganParticipant @michaelgilligan61133]

I’ve never examined one ‘in the flesh’ … but I have always [dangerously] presumed that the gear was skew-cut to match the lead of the worm.

It would help a lot if Andy could provide photographs of his badly-worn component.

MichaelG.

[bernard towersParticipant @bernardtowers37738]

Im with you there Michael just as they do worm and wheel sets for rotary tables etc.

[JasonBModerator @jasonb]

Thrre are plenty of reasonably priced worm and wheel sets on ebay, you would have to change the pair and go with 1MOD which is the closest to 24DP but I can’t see any that go down to 10T, most start at 15 or 20T

HPC do 24DP worm wheels but only down to 12T and at a price

Not sure how much swing there is in the unit as it may accomodate the larger tooth counts but feed rate will be altered.

[HopperParticipant @hopper]

If it is only for feed and not screw cutting, so exact ratio is not critical, Aliexpress has a huge number of worm and wormwheel combinations for sale in all kinds of sizes from model car to industrial scale. Might be something there where a pair of metric  worm and wheel could be substituted. If you can work out the original DP, then you can find the nearest metric Module that would possibly substitute.

Otherwise, you could cut your own skew gear to match the existing worm. Skew gear has straight teeth , but cut at an angle to match the helix of the worm. If you go down that road, it might be worth reading Ivan Law’s book on Gears and Gearcutting (WPS) and both of GH Thomas’s books that have a bit about cutting skew gears to match worms. It works well for things like dividing heads because it only has point or maybe line contact between worm and wheel. Proper wormwheel gives full face contact so is better for power drive such as your application.

In which case you would have to hob a proper wormwheel, which is another whole can o’worms.

[Andy_HParticipant @andy_h]

Thanks for all the replies.

Yes, it does engage with a worm and yes the gear does have straight cut teeth.

I’ve attached a photo as requested.

Did an hour or so of searching last night and it seem a gear of that spec, at least from a supplier within the UK, is pretty allusive – but I will continue searching.

Yes it would take a slightly larger wheel but I haven’t yet measured to work out how much bigger that could be.

I was interested in the comment:

>> If you can work out the original DP, then you can find the nearest metric Module that would possibly substitute.

I’ll have to look further into how to work out that conversion – not something I am currently familiar with. But it’s an attractive proposition as a metric equivalent will be much easier to locate – and also very much cheaper so it’s worth taking a “try it out chance” and if it fails it won’t have cost a lot of money!

Andy

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for posting the photo, Andy

… it’s a bit hard to tell which surfaces were machined, and which were formed by the worm, but it certainly needs replacing !!

MichaelG.

[JasonBModerator @jasonb]

I gave you the original DP based on the 10T and your 1/2″ diameter which works out at 24DP.

There are plenty of calculators or conversion charts online which will show that 24DP is 1.0583 MOD therefore 1MOD is the closest commonly available MOD size

If it is straight cut then 24DP gears can be found from the likes of HPC but unlikely to be 14.5pa. the small tooth cound makes it harder to find from the cheaper suppliers who tend to start at 12 or 15T

[HopperParticipant @hopper]

Note that if you change one gear from say 24DP to 1Mod, you have to change the matching gear or worm as well. A DP gear will not mesh with a MOD gear or worm, they are not that close. If going metric, you would need to buy the pair, both worm and wheel.

[Michael GilliganParticipant @michaelgilligan61133]

Some useful photos, and a video, here:

https://www.suffolksteam.co.uk/flexispeed-meteor-ii-2-lathe

MichaelG.

[Michael Gilligan]

On Michael Gilligan Said:

Some useful photos, and a video, here:

https://www.suffolksteam.co.uk/flexispeed-meteor-ii-2-lathe

MichaelG.

Michael

That is a Flexispeed Meteor 2 rather than a Flexispeed Mk 2 (that I have).

Although the later Meteor (1 and 2) was based on the earlier versions but not identical.

One of those differences judging by this photo is the Meteor 2 used a larger gear on the leadscrew and it was attached to the leadscrew by mean to a screw in the boss of that gear.  In contrast the Flexispeed Mk 2, annoyingly, has a much smaller gear and, even more annoyingly, is attached to the leadscrew by a combination of friction fit on a taper and riveting over the end of the leadscrew!

Andy

[Michael GilliganParticipant @michaelgilligan61133]

Sorry for wasting your time

[Michael Gilligan]

On Michael Gilligan Said:

Sorry for wasting your time

Not at all – thanks for taking the time to make suggestions!

Andy

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