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Victoria 7" flywheel on a 7x12 lathe?

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Lainchy10/10/2019 11:11:19
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Hi Forum,

I've looked all over the place for this... maybe I'm not wording the search properly...

I'm looking for anyone who has managed to machine a Stuart Victoria / Beam / Half beam flywheel on a 7x12 lathe. I believe the swing is 180mm which should "just" be possible... but I'm wondering BEFORE I spend my pennies

I have a Chester DB7, (Warco WM180 alternative)

Just wondering if anyone has managed this?

Cheers

Ian

JasonB10/10/2019 11:16:12
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Neil has had a few big lumps of CI on his so flywheel should be OK. To get the best of the motors power go for carbide inserts, reasonable speed and light cuts rather than slow and deep.

Edited By JasonB on 10/10/2019 11:18:07

Neil Wyatt10/10/2019 11:25:39
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You may need to grind off any casting flash first, but you have a margin to spare.

You will also need to use something like a left-hand tool mounted lengthwise in the rear slot of the toolpost to reach around the rim of the flywheel.

Keep the revs low, and don't run the lathe for too long without a break for a cooldown.

Neil

Lainchy10/10/2019 11:27:05
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Heckers! That's a big lump of CI! :D

Would I still need to get under the crust on the first cut? Say... 150rpm 10 thou? or is that very optimistic?

I can go with lighter cuts once the skin has gone.

The DC brushed motors scare me at slow speed! If I do change, I'll possibly go SC4 or similar after using the Axminster one on the small engineering course.

JasonB10/10/2019 11:29:32
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Would not worry about any crust if present using inserts, 10thou should be OK but I'd be at about 400rpm

Lainchy10/10/2019 11:37:16
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Brilliant.. thanks chaps! Warwick show is looking expensive now

Andrew Johnston10/10/2019 12:15:49
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Even on an industrial lathe some fiddling is required to machine near capacity. This flywheel is over 2" smaller than the listed capacity in the gap, but look at the overhang on the top slide, along with a LH boring bar:

flywheel_rim.jpg

Andrew

Lainchy10/10/2019 12:21:12
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Thanks Andrew. I think I need to just bite the bullet and try it. I can always borrow a friends lathe which would manage it easily if required (and if he allows )

not done it yet10/10/2019 13:38:27
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I would have thought there is little point in a seven inch lathe not being able to machine a workpiece of seven inches diameter? Inevitably the outside rim will need to be cut with a tool protruding at least the width of the rim - unless the rear tool post possibility is miraculous?. Either the tool or the post has to clear the edge.

I would have thought that the casting may need cleaning up a bit to clear the bed, but then just slow-going around the circumference.

Is the lathe truthfully specified as 180mm ‘centre height’ or ‘swing’? There will be a very slight difference.

Assume you are going to use TC tooling? The recommended surface cutting speed for HSS is likely less than the minimum for your lathe - and I would not want to be using one of their variable speed drives at, or near to, the minimum rpm, without extra cooling, at any sort of loading and sensible machining time.

Neil Wyatt10/10/2019 13:56:59
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Posted by not done it yet on 10/10/2019 13:38:27:
 
The recommended surface cutting speed for HSS is likely less than the minimum for your lathe - and I would not want to be using one of their variable speed drives at, or near to, the minimum rpm, without extra cooling, at any sort of loading and sensible machining time.

First generation brushed Mini-lathes will go down to about 50rpm - you certainly don't want to be cutting at that sort of speed, but a sensible speed of HSS is achievable.

Neil

Edited By Neil Wyatt on 10/10/2019 16:06:14

not done it yet10/10/2019 14:44:47
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I was just looking at the new specs - for a chester db7vs - they quote 50rpm as minimum. Warco quote zero for the WM180 (0-1250? On ‘lower speed band’. Not much else to comment on. Still would not load up the motor at slow speed without extra cooling.

My lathe will go down below 40rpm at the spindle with the motor running at 50Hz, but I would not want to work it hard for any long time at below 25Hz, although it will run happily much slower on light loads, at least for short periods. I reckon my lathe is far more resilient to low speed operation than any chinese option.

Lainchy10/10/2019 14:58:08
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I'll certainly bear it in mind... and indeed, in the past, when parting steel... I've pulled the tool back out and run the motor up to higher speed to help cooling. It's just something I'm aware of. The Chester (an I assume Warco) starts at about 50rpm.

I will be roughing out with TC insert tooling, and finishing with HSS.

JasonB10/10/2019 15:52:05
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Working at max diameter you may well find the machine just stalls at 50rpm, different if you are running that speed and say threading M6 where the diameter is much smaller. That is why I advocate 3-400rpm and not too deep a cut. My 280 will happily do 10" flywheels at 300rpm but just comes to a stop if I take the same DOC at 50rpm, Brushless and inverter versions are better but may still be stalled.

Lainchy10/10/2019 16:01:29
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Thanks Jason

May well pick up the Victoria or even a half beam at the show. S50 first though... plenty to learn.

Bazyle10/10/2019 17:35:28
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There are other ways. If say you decide on something with a 10 in flywheel will you feel obliged to get a 10 in lathe? Apart from the, rather unnecessary, height raising designs that have been around for years you sometimes need to get out of the mindset of using the lathe only as it was intended.

How about making a jig to ensure a true hand drilled hole in the centre. Then mount on a spigot on the cross slide and slowly turn by hand against an end mill or flycutter in the spindle. Think of your lathe as a general purpose mounting system with some parts that can be moved precisely and other parts that can provide rotating motion.
If you did want to run it as 'normal' but are concerned about low speed torque use the flywheel itself as a pulley rigging up your electric drill at the front such that the belt leaves a gap where the tool is cutting.
Generally get more adventurous.cool

not done it yet10/10/2019 19:03:55
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Poster has a mill. A rotary table could be a useful investment. Just another way to get the result required?

Lainchy10/10/2019 20:49:32
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Thanks guys. I bought my Chester lathe due to budget... I knew I'd need lots of tooling too. I kind of didn't expect to be thinking about larger flywheels at the time of purchase. I knew I wanted to build something S50/10V/10H size, but now that I've started on my engineering journey (very beginning still) I am tempted by the bigger kits.

My mill is the WM14, and, I have already bought a 4" rotary table to fit + 4 jaw and 3 jaw chucks for that. I'm guessing I could bolt the flywheel down to that then? and use an end mill to clean around the circumference? I'd be concerned about getting things concentric maybe... but... if the lathe is out... there's another suggestion! so many thanks!

not done it yet10/10/2019 22:36:24
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Be wary of the quality of your rotary table. Some do not last long with ‘circumference’ cuts. It is often safer to make multiple plunging cuts and simply clean up with a conventional direction final cut. Climb milling may be something to avoid at all costs. Of course, not all are like that, but....

Lainchy10/10/2019 22:43:26
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...likely. It was a Warco purchase, and not their top of the range. I bought it to round conrod ends on the S50. Tried climb milling.... very very light cuts only

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