Petros any updates on your experiment? I am thinking about adding another 1/4" plate to make it a total of 3/4" and reinforce the webs etc...
let keep this thread going and see everybodys little stiffening experiments
twist the bed and the results were +0.07 and - 0.08Lawrence the reason I used these kind of steel beams as a base is (because of their shape) they felt pretty stiff when welded together. So after I have bolted my minilathe (7x12) on the base I did the initial test trying to twist the bed and the results were +0.07 and - 0.08 (I probably can push more than pull with my right hand!).
to try for better results I think is like chasing my tail, as other problematic areas of the lathe (e.g. the toylike tailstock) ruin it's accuracy.
For a cheap "made in china" lathe when I make light cuts, I think its pretty accurate now!
regards
Petros
Lawrence I'm not an expert but I think that a flat plate does not provide the stiffness you are after.
Geometry teaches us that forces distributed to different shapes differ tremendously try a solid thick flat cardboard and a pizza box (with cover glued) ! The pizza box is way less flexible!
I suspect that if you make a box out of your two plates, the distance between them and the new geometry, will make it many times stiffer compared to two of them one on the top of the other!
See here for some details!
View attachment 130515
But as I said I’m not an expert!
I just made my base on the above idea!
Petros
twist the bed and the results were +0.07 and - 0.08
you did mean .007" -.008" ?
..with most thing in my life i rarely have the correct items to do the job and often use what I have on hand.....
...what it comes down too is thickness the thicker the better = more stiffness.
+0.07 mm -0.08mm total flex about 0.15mm
Take into consideration that it is a 7X12 mini lathe! Im' not sure that the base could be that stiff it was 7X16!.07mm! wow that's excellent!
Precision ground plate steel will cost more than cold or hot rolled steel. It does here anyway.
Then I took it to extremes and had a friend with a larger mill machine the lathe bed's feet so that they were matched flat and parallel to the bed ways. Then bolted it down to the plate. Made the lathe much more stable, but the modifications started pointing out weaknesses in other parts of the lathe, as you are discovering with the motor. The compound and saddle is another weak area. And the tailstock... Like building a race car from a production street car: Once you start modifying one area, horsepower for example, other components must be redesigned/modified to support the increased power. But the time you're done, you've completely modified the car.