Is your lathe big enough

In ME 4477 page 364 is the start of a new article concerning a Garrett stationary engine. Anthony Mount states "The model fly wheel is 152mm (6 inches) diameter so well within the capacity of most models engineers' (sic) equipment."

Is this true, do the majority of model engineers have a lathe big enough to turn a 6" fly wheel.

In other words are there more owners of Myfords than mini lathes out there

Edited By Eric Cox on 05/03/2014 15:54:28

Edited By Eric Cox on 05/03/2014 15:55:35

Yes

Thats also why the majority of stationary engine kits don't have flywheels over 9" so they can still fit the gap in a myford bed

Oh and the generic mini lathe can swing 7" so whats the problem?

The good thing with Anthony's designs is they can all be fabricated anyway so just scale down or up to fit the machines you have and what takes your fancy, Just look at all of Mr Boxhalls small versions that took several gold medals at Sandown.

Edited By JasonB on 05/03/2014 16:03:26

While I don't own a Myford, I have a lathe that will swing more than a mini, does that put me in the minority?

I have a Sieg C3 too....

I don't know if Anthony will remember, but several years ago I met him at MMEX and said I loved his designs but they all had 8" flywheels (requiring the gap on a Myford), too big for the 7 1/2" swing of my mini lathe.

So is this all my fault?

Neil

My Warco 220 (Mashstroy C218T) has a centre height of 105 mm. Therefore it should be able to handle a 8in diameter flywheel. I have never tried it. It does have a 200mm dia faceplate.

The above is the strict answer to the original question, but on the general basis of is it big enough, then no it isn't as I would like a little bit more. Centre Height that is! Indeed, if I knew 25 years ago what I now know, then I would have bought a Boxford ME10 or 10A lathe.

Regards,

Peter G. Shaw

Edited By Peter G. Shaw on 05/03/2014 20:28:14

Hi Eric,

When I bought my C3 mini-lathe as a beginner two years ago, I thought it would do me for quite a few of the Stuart engines. After doing the 3" flywheel on the S50 I'm not so sure. In theory it has a swing of 7" and I know there may be ways of turning the outside of a 7" flywheel but wouldn't feel confident spending the £235 on a Stuart Beam engine kit (which might be next) without the nagging feeling that I might need access to a bigger lathe.

Gary

Just a thought:

Is there an opportunity here? ... a market niche for some enterprising supplier.

Woodworkers have special "Bowl Turning" lathes available, so why shouldn't Model Engineers have something similar, dedicated to large-diameter/short-length jobs? ... I suspect that many modellers could more easily find room for two compact machines, than one big 'un [and it's very rare that we need to work on components that are big in every direction].

There have been industrial-size machines but; so far a I am aware, nothing on the miniature scale.

MichaelG.

[quietly waiting for all the corrections]

Edit: Here is an interesting home-built bowl-turning lathe that demonstrates the concept.

Edited By Michael Gilligan on 06/03/2014 08:37:43

Your lathe is never big enough. There is always something that will not fit in it. One option for turning larger diameters is to fit riser blocks under the headstock and tailstock to raise the centre height. This will place bigger loads on your lathe so only take lighter cuts. Machining accuracy depends on how good you make the blocks.

Something like this might be useful?

**LINK**

Edited By V8Eng on 06/03/2014 09:28:10

LOL, LOL, LOL. Oh yes!

Martin.

I've got a Chester DB8, ie it will turn 8" dia. or just a bit over and does most things I need. Now this is where some of you might like to look away. Ready. I had a face plate job involving squaring up an angle plate and it was just too big to swing. Tried setting on cross-slide but to flimsy and no room.. so I thought a bit and then ground off the top of one vee . about 1/2" long and close to headstock. Just enough room and did the job. Can't say I've noticed any affect on the lathe.

In my case the other day the answer was "only just". I had planned to shorten a pair of cycle cranks, overlooking the fact that the spider carrying the chainrings projects slightly more if the outer spider arm is in line with the crank (some have the inline arm inboard). In the event, I was just able to get the job in by removing the sheet cover to the bed. My photo shows a 1p coin declining to enter the gap.

Edited By ega on 06/03/2014 10:23:49

Here is my solution.

&" plus machining allowance should be OK on a mini lathe. This was a nominal 6" x4" block. Pythagorus will tell you that's over 7" across the diagonals and I had to grind a small facet at each corner. (sorry I keep using this pic to convince mini-lathe doubters).

A 1" raising block for mini lathes could be a good project/seller.

There's also "lathing in the mill" - I hope to carry an article on this in MEW soon.

Neil

"the merits of a bit of ingenuity and improvisation"

These interesting comments remind me of the "Handmaiden" series by the late T D Walshaw in ME - as I recall, a small steam engine built almost entirely with hand tools.

No "were" about it. Full sized power station steam turbine rotors weighing 80 tons are machined today by much the same method when doing a blade change or rebuild etc. Set between centres on trestles and driven by an electric motor and machined with slides bolted to the deck. Onsite machining, it's "the latest thing" doing away with the "old" way of sending the 80 ton rotor to the manufacturers works in another city to be machined in a rather large lathe.

In the home workshop, perhaps a too-large flywheel casting could be drilled and reamed or even bored in a good drill press. And a good sized drill press could be pressed (ow, skuse the pun) into service as a vertical lathe by putting the flywheel on its shaft, gripping shaft in drill chuck and bolting the top slide off your lathe to the drill press table by means of angle brakcets etc. Bottom of the flywheel's shaft could be located on a centre or even a bearing attached to the table. Vertical lathe was the way most machine shops did their large diameter flywheels in t'old days and if you google them, you can see some of them were a pretty crude machine but got the job done.

Depth of cut on the home drillpress vertical lathe could be controlled by loosening the mountings and tapping the slide inwards a tad at a time. I've seen a lathe in a steel mill turning giant rollers 6 foot diameter with a toolbit clamped straight to the carriage and depth of cut controlled by loosening the tool clamp and whacking the 1-inch square toolbit with hammer to nudge it in to take a new cut. Just got to get back to basics.

And the day was when every apprentice were taught to file a block of steel straight, flat and square, which enables you to make just about anything -- given enough time!! -- from solid stock.

But I should think that a 10" flywheel could be made in a small lathe by turning the hub and spokes in the normal manner, inserting the spokes into holes drilled in the hub then cutting the rim out of stock and filing it to final shape - or get the local engineering works to cut a circle of plate with their plasma cutter and finish it off with an angle grinder and file. Cut it into segments, drill for the spokes, assemble and join the segments with concealable bolting plates, welding .

You don't need a big lathe if you have an even bigger mill.

The methods I posted on making my Galloway cart wheels could easily be used for larger flywheels and the 10" one I made for my Easton & Anderson could be done without a large lathe quite happily.

Edited By JasonB on 06/03/2014 15:38:51

I did the final turning of the flywheel for my Leak engine by clamping down a compound table next to the flywheel and running the engine on compressed air. (I know marine engines normally don't have flywheels, but in the steam launch size they are well worth having.)

The crankshaft was milled between centres to near size, then ground to finish. The only turning done was truing up the outside of the balance weights between centres on the Myford, which it could just do. The saddle had to be outside the webs, with a long tool reaching in, since the webs and balance weights only just cleared the bed, let alone the saddle.

The 3" bore HP cylinder was also bored on the Myford. The outside shape cleared the bed by about 1/8". It took a bit of cunning to mount it on the faceplate.

John

why would you ever want to worry about such a problem?

isnt that why most of us are members of a club - with much larger machinery to use for very occasional one off jobs? or fellow club members who have much bigger lathes?

my lathe is quite small but very accurate. when (perhaps once every 5 years) ive needed to turn quite big stuff ive had the benefit of using a fellow club member's big Holbrooke lathe or the club machinery. i have neither the room, electricity supply, or money to justify anything bigger than what ive got which fulfills all my needs 99.9% of the time!

cheers,

julian