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Stiffening A Mini Lathe Bed
- Thread starter petcnc
- Start date
- Joined
- Dec 29, 2012
- Messages
- 394
Lawrence 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
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
- Joined
- Dec 29, 2012
- Messages
- 394
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!
But as I said I’m not an expert!
I just made my base on the above idea!
Petros
I understand the analogy well...and you are correct..with most thing in my life i rarely have the correct items to do the job and often use what I have on hand......I have these plates......I do not have a welder to cobble up a box like yours even to weld them together
another good analogy... a simple 2x4 when using it as a pry bar works much better when you stand it on end long wise...what it comes down too is thickness the thicker the better = more stiffness.
- Joined
- Dec 29, 2012
- Messages
- 394
+0.07 mm -0.08mm total flex about 0.15mm
- Joined
- Dec 29, 2012
- Messages
- 394
- Joined
- Dec 29, 2012
- Messages
- 394
Take into consideration that it is a 7X12 mini lathe! Im' not sure that the base could be that stiff it was 7X16!
- Joined
- May 16, 2016
- Messages
- 1,695
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.
If you are going to continue to spend all this money and time to try to improve your lathe, why not bight the bullet and buy a bigger better lathe. Every time time you fix one fault another will follow it. Putting a bigger motor on it will only overload the drive train and induce even greater twisting forces on the bed You might get a way with going from 300 w to 500 w but to go any further would be asking for trouble. Lengthening the bed would be fraught with danger and probably not very successful.
Good luck,
Bob