Thread: improving a lathe cabinet

i drew up some dimensions after looking at how best to use whats on hand the pictures below should explain it well oh the renderings show box but i intend to use C-section the boxers under both cabinets are going to be "spliced" in so the height wont change and they still remain ridged







ok i know this isn't the place for a build thread so if no one can give me any technical advice i might start a build thread in the fabrication forum

You may do better in the fabrication forum. The first thing that struck me about all this is that you need to identify where the flex is in the existing support cabinets. That means pushing different corners in specific directions to see how much movement there is and where it's coming from. Then you add elements to stiffen those areas.

I see two problems with your initial ideas - those lengthwise C-sections you've attached aren't braced to each other, so while they may stiffen the structure a little, the design isn't as stiff as it could be, and will still twist on the vertical axis. Thus I think you need to consider how to brace the elements you are adding to ensure stifness in all axes.

Secondly, I don't think you necessarily need to extend the footprint as you have - if the chassis is stiff, then the only movement you might experience is a corner lifting from the floor. The best solution to that would be to dynabolt the corners.

thanks for your reply Rusty i only realized i should have put this thread in the fabrication forum after i made i had thought it was mostly for trailer builds ill see about getting it moved

ok i can see it now the extra large feet and cross rails make the cabinets stronger but wont stop it from twisting hmm this needs some thought.... my reasoning for widening the feet was from experience with better industrial machines these Chinese lathes have narrow beds probably to use less iron anyway the stands are just a bit smaller than the overall width of the lathe its self (rear motor included) and that makes big problems with rigidity the same size lathe made in Japan or Europe would have a base much wider, my ideal seat up would be a base similar to this Harrison i think i could add some 25mm box section to help brace it

one question for tonight would removing the feet on the tailstock end of the lathe help leveling and prevent unintended twisting?

Originally Posted by new_guy90

one question for tonight would removing the feet on the tailstock end of the lathe help leveling and prevent unintended twisting?

The first question you should ask is whether the problem is in fact with twisting around in the vertical axis, or is the cabinet flexing in other axes. If the chassis is not stiff, removing feet won't help, as it'll still flex despite one end touching the ground.

Looking at the original pic, if you could just concrete-anchor (dynabolt) those cabinets to the floor, 4 points under the headstock and maybe 2 under the tail, maybe using small C-section as a spacer at one end to achieve level, you may find a lot of the flex goes away, since if the bottom of those cabinets is fixed firmly to the concrete their box section should be reasonably stiff.

Originally Posted by RustyArc

The first question you should ask is whether the problem is in fact with twisting around in the vertical axis, or is the cabinet flexing in other axes. If the chassis is not stiff, removing feet won't help, as it'll still flex despite one end touching the ground.

Looking at the original pic, if you could just concrete-anchor (dynabolt) those cabinets to the floor, 4 points under the headstock and maybe 2 under the tail, maybe using small C-section as a spacer at one end to achieve level, you may find a lot of the flex goes away, since if the bottom of those cabinets is fixed firmly to the concrete their box section should be reasonably stiff.

sorry for the confusion but the problem isn't flex in the bed but vibration in use and because of the slope in my shed the headstock cabinet sits 80mm high off the concrete a concrete platform is out of the question and so are dynabolts at this stage im flirting with the idea latter but i would still like to beef up the cabinet both size wise and weight and then ill shim the lathe into final alignment

Gidday

As part of maintenance @ work & upgrading our machinery Ive helped install large industrial machinery like brake presses and guillotines. The most important factor in keeping these stable level and rigid is the footing.

We actually poor a slab larger than the footprint of these machines @ least 1.5 meters deep & incorporate a rio skeleton inside the slab with anchor points to attach huge heavy duty high tensile fasteners to the machinery.

My point being that its often underestimated how much 'flex' movement etc etc can come from a poorly seated piece of machinery. Id ditch the present setup your using to foot your lave and either poor some level footings or use steel packers to level her up and ensure its securely dynabolted/Chemsetted reasonably deeply into the floor.

You might be suprised @ how much difference this makes...........................

Regards Lou

unfortunately i cant poor a new slab for it to sit on i contemplated that when i fist put the lathe in im open to dynabolting it down but with the slope im just not sure ill be able to level it correctly.... i was thinking of 2 steel pads one bolted to the floor and the other used with an adjusting bolt then when everything is level and after some time for it to settle ill weld the pads together then when it all needs to come out the only think left on the slab will be a few holes

i drew up a few more ideas here they are

Looking at the amount of fabrication that maybe involved in strengthing the Cabinets to give you more ridgidity,have you consider replacing the entire base with a Fabricated frame purpose built to suit your floor.

You would just use the Swarf tray and replace everything under it,you would have to increase the Footprint greatly if at all.

If you went down this route it would probably be better to use SHS or RHS with 5mm wall.

[QUOTE=new_guy90;1227861]unfortunately i cant poor a new slab for it to sit

You dont have to poor a new slab just some reasonably sized footings shouldnt be too hard n that way you can ensure their level......................

After that if you really must you can add a few gussets n braces Would be a lot easier then re-engineering everything else in a costly manner..............

Regardless whichever way u go good luck with it!!!!!!!

Lou

alright i have refined the design a fair bit more now and i really think it has promise the only thing i have changed is the width from 835mm to 800mm for simplicity sake. Im still not sure how im going to make the leveling feet i think ill use the biggest bolts i can get and turn some special nuts to weld into the base and use a lock nut to tighten it all up but anyway still plenty of time to think of that onto the pictures

this first one shows what i want the cabinet to look like when im done except the outward feet will have thick sheet welded over them to clean it all up and im thinking of putting a foot brake between the feet i worked out it it would be out o the way during normal use


i took the chip pan off for this pic oh the components in brown are the C-section the green bits are 25X25mm box section, the yellow triangles will probably be 6mm guillotined sheet offcuts from work and obviously the purple in the above pic is the chip pan and the blue is the stock cabinets


this picture shows how all the welded components with out the cabinets got together


i want to thank you all for giving your input into all this i have been cutting components after work and ill have more cut this weekend so next up will be taking a leap pulling down the lathe and welding this bad boy up

Edit: just found this thread it looks like a promising idea but not a route i want to take

Are the actual cabinets sturdy enough to keep as your structural elements? It looks to me like you'd be better off making your rigid frame from and sliding the cabinet boxes into some carefully crafted gaps in your frame. Cheers - Mick