- Joined
- Dec 29, 2012
- Messages
- 394
I have a mini lathe 7X12 under the name “Clarke” that I have bought from UK some 5 years ago.
As you can see, the lathe sits on a wooden table without any other support and rests on 4 rubber feet (that you cannot see).
It behaved ok so far without any problems having very light duties though.
As I sought a better lathe out of my Clarke, I made a few improvements to gain in accuracy.
To name a few of the improvements (That you can see to other posts if you scroll further down) I changed the bearings with tapered roller ones, I lowered the topslide to be able to use 12mm (1/2”) tools, I made a number of changes to the tailstock and bought a pair of 5” chucks to replace the hectic 3” ones the lathe came with.
Although I made all these changes and adjust every aspect I could, the lathe remained very “delicate” and even my breath could ruin it’s accuracy.
The best I managed to achieve was to cut a bar, supported between centers, achieving an accuracy of 0,01mm, end to end, to a length of 250mm (12”) with very light cuts. Most people would be happy with these results but I was looking for something better than this.
Moreover, what puzzled me was the lathe’s tendency to ruin this accuracy when I tried a cut deeper than 0,25 mm (0.01”)! I knew I had to do something about it but for years I was leaving it for “later” and this later took 5 years to come!
Seeking info to the net, I found that the weak point of the mini lathe is the bed and its tendency to bent under stress. This seems to be the main cause of its poor accuracy results. Having set the TDI at the end of a bar supported on the chuck I tried to twist the lathe by pushing the head and pulling the tailstock. To my surprise the TDI moved 0.5 mm (0.2”). It was time to do something about it to reduce this flexibility.
I have some old steel beams 80X30mm having a thickness of 3mm.
I thought that If I weld 2 of them together I could make a base strong enough to bolt my lathe on it to make it less flexible.
The idea was to bolt the lathe on it to give extra rigidity to the bed
So I cut them weld them drill them and put the lathe on it.
I used long bolts to secure the lathe on the base.
And an extra nut between lathe and base to level the bed.
Lathe fits beautifully on the base and I gained the extra rigidity I wanted.
Now it moves only 0.15mm when I try to twist the bed.
Thank you for reading
Petros
As you can see, the lathe sits on a wooden table without any other support and rests on 4 rubber feet (that you cannot see).
It behaved ok so far without any problems having very light duties though.
As I sought a better lathe out of my Clarke, I made a few improvements to gain in accuracy.
To name a few of the improvements (That you can see to other posts if you scroll further down) I changed the bearings with tapered roller ones, I lowered the topslide to be able to use 12mm (1/2”) tools, I made a number of changes to the tailstock and bought a pair of 5” chucks to replace the hectic 3” ones the lathe came with.
Although I made all these changes and adjust every aspect I could, the lathe remained very “delicate” and even my breath could ruin it’s accuracy.
The best I managed to achieve was to cut a bar, supported between centers, achieving an accuracy of 0,01mm, end to end, to a length of 250mm (12”) with very light cuts. Most people would be happy with these results but I was looking for something better than this.
Moreover, what puzzled me was the lathe’s tendency to ruin this accuracy when I tried a cut deeper than 0,25 mm (0.01”)! I knew I had to do something about it but for years I was leaving it for “later” and this later took 5 years to come!
Seeking info to the net, I found that the weak point of the mini lathe is the bed and its tendency to bent under stress. This seems to be the main cause of its poor accuracy results. Having set the TDI at the end of a bar supported on the chuck I tried to twist the lathe by pushing the head and pulling the tailstock. To my surprise the TDI moved 0.5 mm (0.2”). It was time to do something about it to reduce this flexibility.
I have some old steel beams 80X30mm having a thickness of 3mm.
I thought that If I weld 2 of them together I could make a base strong enough to bolt my lathe on it to make it less flexible.
The idea was to bolt the lathe on it to give extra rigidity to the bed
So I cut them weld them drill them and put the lathe on it.
I used long bolts to secure the lathe on the base.
And an extra nut between lathe and base to level the bed.
Lathe fits beautifully on the base and I gained the extra rigidity I wanted.
Now it moves only 0.15mm when I try to twist the bed.
Thank you for reading
Petros
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