Thread: Mini lathe Design

Hi there. I would think you want the centre of gravity as low as possible to give stability.
I'm no expert it's just my 2 cents worth.

Cheers,
Peter

Originally Posted by woodtryer

Hi there. I would think you want the centre of gravity as low as possible to give stability.
I'm no expert it's just my 2 cents worth.

Cheers,
Peter

Woodtryer,

That was actually my original thought, ie weight down low, or not too top heavy.

But this only a mini lathe, an nothing ever big gets spun on it, definitely not anything way out of balance, we have a bigger lathe for bigger stuff.

My thoughts we’re having a center of mass right under the lathe(Box filled with dry sand) may be better, than having the mass of weight down near your feet,??????.

Cheers Matt.

I agree with Peter, centre of gravity must be low for stability and safety.
Even if the lathe is used only for light work, any imbalance, coupled with centrifugal force at speed, will be far more difficult to control when centre of gravity is high.

Just my 2 cents worth

Fryers

Laws of physics and gravity suggest that the weight should be lower rather than higher to create better stability.

Matt

I agree with everybody who has said place the weight down low for stability, bit I am not convinced that is the issue. To my mind you are looking to dampen out any vibrations or other harmonics that may be present. To achieve that the solid mass needs to be placed close to the source of vibration otherwise the vibration simply carries down to wherever that mass has been situated and the lathe sits atop wobbling. The Tough had some 200mm channel placed on top of the twin cabinets and the other had a similar piece of channel facing up and filled with concrete. The ends were blocked off and straps placed across the channel where the lathe was bolted down.

Some pix of the Tough lathe are here (post #6). I think the channel was 200mm wide.

And the other lathe:

P1070345 (Medium).JPGP1070348 (Medium).JPG

It also has concrete triangular legs, but that would be quite unnecessary for your purpose.

I would suggest you can pick up a piece of channel from the scrap metal merchants. Two pieces of 100mm or 75mm channel placed alongside each other and welded together would do the same job. As you are talking about filling with sand, it is only the next step to mix in some cement.

Regards
Paul

I agree with Paul on this one. I think if the legs are sufficiently splayed then the low centre of gravity becomes a furphy. It's about dampening vibration and having the mass too far from the source allows harmonics to be set up. You need a good nudge to lift the system out of its low potential energy well to where the centre of gravity become important. I would have it high, design in a good splay and run stretchers in at half height as well.

Paul ,Mic,

Yes the real issue is vibration damping,
It’s not about trying to stop a lathe doing a silly dance across the floor.
But that’s my fault for not being more clear, apologies everyone.

I will another drawing now with more of what I have in mind,

Stay tuned.

Cheers Matt.

Ok
A better technical drawing, [emoji849]

Top to be around 100 mm thick internal web, back filled with dry sand.

Legs to be 100 mm thick internal web designed back filled with dry sand.

I think I also include a gusset through the middle(Not draw in yet)

This is all to aid in damping down vibrations,

Turning pens, when you are doing your final last pass, trying to remove a Bees pubic hair, any movement is a pain the behind.
An of course no prober Turner would ever think of using sandpaper [emoji849][emoji849][emoji849].

So it might seem a bit over the top, but I’m kind of getting over throwing stuff together, an I fix that later, I’m sure there’s plenty here who know we’re I’m coming from.

So build this once build it over the top [emoji41].

Cheers Matt.

Hi Matt;

Agree with Paul and Mic; if you want to dampen out vibration the easiest way is to add an inflexible mass as close to the centreline of the lathe as possible. Generally this is only really achievable by bolting the lathe bed to something solid and heavy.

However… if this is a generic mini lathe made from cast iron; and Sally is only turning pen blanks (and possibly handles) then I really wouldn’t worry about it. A turned 3/4” blank can only be a couple of grams out of balance; hardly enough to worry something weighing 20kg+. I would be more concerned about the pen mandrel flexing more than the lathe moving around!

At our guild we run a pair of Vicmark VL100’s on old MDF cabinets sitting on casters; these are taken to shows or craft fairs etc for demos and the the guys knock out pens, spinning tops and similar items with zero issues.

Actually; Bdar regularly knocks out considerably larger items on one of them pretty much full time; he made a 5” Huon Pine bowl out of a 6X6X2 blank for My Beloved on it. He wouldn’t put up with stuff shaking around…
Resized_PhotoRoom-20231025_145755.jpg Resized_PhotoRoom-20231025_145541_(1).jpeg

Heh. I must be getting old, turning conservative... 'cos I reckon down low is the go.

For two reasons: it's a mini-lathe. If it ever vibrates enough to be a worry then either the blank is well 'n truly unbalanced or the lathe has some serious issues. Weighting the top wouldn't be the best solution to either.

Second reason? I wouldn't have a "plank" type top to it at all, let alone one I could weight. I'd leave it an open framework so the minimum of crud builds up underneath the lathe. Perhaps with an angled board underneath to deflect the aforementioned crud out the front and not on top of whatever's stored underneath. (Although it'll still end up covered. Such is the way of lathes. )

Having built several lathe stands and couple of lathes. My thinking now is build a heavy stand to start with and as wood is a good vibration damper the heavier, the better, make the lathe sure is well secured to the stand as the vibration is transferred mechanically, you could bolt it down but on a mini maybe it wont be necessary. But I would be looking to add something like this feet Just a moment...
If the vibration is intense, you can glue the anti vibration rubber to cork sheeting much like ply wood in sandwich making sure the rubber is to the bottom , a couple of layers of each.
Within the stand, allow for as much sand as think is required, and perhaps 20-30% more. This weight will keep the lathe secured down on the pads.
These sort of layered or composite pads are common in the medical field for vibration dampening and work very well.

I have Woodfast Midi lathe on their metal stand due to space issues I have fitted the Kreg wheels set. I have no issues when turning pens and small items. with slightly larger items I lock the wheels. I also over built a lower shelf on the cross bar out of 25 mm thick particle board on this I place my lathes extra tool rests and my spare chucks and lathe drill chuck which all helps stabilize the lathe as well. Its works for me for last 10 years
Regard Michael

It’s done,
Some 90/35 mm pine, one sheet of 12 mm ply from Bunnies land not marine grade just cheap stuff.

A left over Cypress pine post 120/70 mm an some gluie stuff an those short thin wire bits that come out very fast from my Makita Brader,
Plus one bag of concrete, dry.


A happy client too boot.

I really should give it a wipe with some Wipe on Polyurethane as well.

760 mm high 800 mm long an 235 mm wide

Perfect hight for a Shorter Turner





No looking closely, it’s throw together quickly model.

Cheers Matt.

I like it. Looks solid!