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| The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20) |
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| vtsteam:
How would length of time matter? Also, the consequence of yielding doesn't look dire. If there was an issue it would, at worst sag. OTOH the end arm looks severely twisted on the pivot in photo 5, but I'm assuming that's a camera distortion. |
| vtsteam:
Maybe the twist is real? There's not a lot of bearing surface between two square tubes because of their radiused corners. In that case I'd get rid of the single bolt top pivot, then weld ears, top and bottom, on the main arm, and fit the swing arm between the ears and bolt/pivot through. Similar to how you did the main post pivot. You can leave the swing arm longer inside the ears (for more bearing surface) if you don't cut off the arm square, but cut an arc with the pivot-end radius for closer clearance. |
| vtsteam:
One other way of adding swing arm bearing surface would be to locate the swing arm pivot at the back (right side) of the main arm instead of the center, since the swing arm will mainly be used off to the left side. That would give twice the bearing surface of a center bolt plus more than twice the resisting lever arm. |
| mattinker:
I think you'll see whether you need to modify in use! I think we all would have made our own versions! it works! Cheers, Matthew |
| awemawson:
It's surprisingly rigid, the main sag being from me having to slightly loosen the pivot bolt to be able to swing it. I may put a brass or PTFE shim between them to let it still move when a bit tighter. This crane is probably only going to be used half a dozen times, mostly while machining the chuck registers on both sides of that billet of EN24T - it's not as though I'll be changing chucks every day ! . . . but thanks for your concerns - I certainly don't want to drop the 3 jaw - that's a beast of a chunk of expensive steel |
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