# Stiffening A Mini Lathe Bed



## petcnc

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


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## Bob Korves

What are your results now, Petros?


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## rrjohnso2000

Bob Korves said:


> What are your results now, Petros?



Very interested


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## wrmiller

Just above the last pic above he says he now sees .15mm of movement.


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## petcnc

Bob Korves said:


> What are your results now, Petros?



I have 70% better results now. Before the max movement was 0,5mm now is 0,15.
Well I would like it to be zero but I think I can live with it...

Petros


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## Billh50

Very interesting....Since I am going to be starting a bed extension on my mini-lathe maybe I will need something thicker than what I was going to use for the base. Will have to think about this for a bit. I will be posting pics as I go along. Right now I need to clean up both beds and check some dimensions. So far the dimensions I checked look good for the donor bed to work.


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## Tony Wells

Weldments can be a bit unstable. I'd opt for a piece of 3/4" (19mm) plate, blanchard ground.


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## wrmiller

Tony Wells said:


> Weldments can be a bit unstable. I'd opt for a piece of 3/4" (19mm) plate, blanchard ground.



Tony: That is exactly what I did with my Micro Mark 7x16, but didn't want to suggest it as it is a rather pricey solution. Worked really, really well though.


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## Bob Korves

petcnc said:


> I have 70% better results now. Before the max movement was 0,5mm now is 0,15.
> Well I would like it to be zero but I think I can live with it...
> 
> Petros





petcnc said:


> I have 70% better results now. Before the max movement was 0,5mm now is 0,15.
> Well I would like it to be zero but I think I can live with it...
> 
> Petros


Yes,  I saw that, but what are the results now in accuracy on the work?


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## petcnc

Bob Korves said:


> Yes,  I saw that, but what are the results now in accuracy on the work?



Bob I see what you mean! I tried a cut 0.35mm to a bar today. Accuracy is 0.01 as expected to be but...
My mini lathe revealed another weak spot! Motor power. As the motor is just 300W it complained when I was cutting at 0.35mm.
To be honest I did not dare to go deeper to test the accuracy further. I might try it after an extra slow feed speed modification I have in the "to do" list.

Petros


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## petcnc

wrmiller said:


> but didn't want to suggest it as it is a rather pricey solution.



I'm surprised!! 
Expensive? 
Do I miss something?
I thought steel beams are cheap worldwide...
Can you clarify it please?

Petros


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## wrmiller

petcnc said:


> I'm surprised!!
> Expensive?
> Do I miss something?
> I thought steel beams are cheap worldwide...
> Can you clarify it please?
> Petros



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.


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## Tony Wells

No offense intended, but you can only go so far making a silk purse out of a sow's ear, as the saying goes. You've started on that path with a fix for one weakness only to discover another.....then another, etc. At some point, you will need to be content with the performance of the machine, or replace it with something that will fulfill your expectations.


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## petcnc

wrmiller said:


> I 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.



As I dont have such a friend I used 4 extra nuts between lathe and the base. Adjusting the nuts allowed me to level the bed using "Rollie's Dad's method" (I don't have a machinist level either). This way I compensated for any warp (skew is the right word here?) of the base.

You are very true on the discovering weaknesses this way It just messes up your feelings. You are happy you achieved an improvement and sorry to uncover another well hidden one!!!

Petros


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## rrjohnso2000

No need to feel bad discovering the weak point in the machine. You have improved it, the real question is it good enough for you. 

What do you need it to do? Will the cost of the improvements be more or less than a step up in machinery? Or is tinkering with the machine the hobby?

Either way nice work


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## Bob Korves

Instead of doing a bunch of upgrades, just get one of these:
http://lathes.co.uk/monarch/page2.html
instead.


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## petcnc

rrjohnso2000 said:


> No need to feel bad discovering the weak point in the machine. You have improved it, the real question is it good enough for you.
> 
> What do you need it to do? Will the cost of the improvements be more or less than a step up in machinery? Or is tinkering with the machine the hobby?
> 
> Either way nice work



Well the machine does now exactly what it supposed to do: turn a piece of metal roughly 4X20 inches with an accuracy 0.01mm end to end. It is not designed to work hard steel of that dimension not to be used as a part of a production line either.
Am I happy with it? That is a general question that applies to everything we have and do! I would love to have a HAAS cnc superautomatic machine to make a 0.5x1 inch bolt but it woul be an overkill!!!
I'm happy with the little lathe as it is now!
I can also recall that I was also happy with it when I bought it long time ago! 
Comparing it with the machine delivered to me 5 years ago it is a completly different machine. 
Working on it's improvement I have learned so many things both for mine and the machine's capabilities. 



Bob Korves said:


> Instead of doing a bunch of upgrades, just get one of these:
> http://lathes.co.uk/monarch/page2.html
> instead.



Bob nice idea but the deeper I dig the more problems come to the surface.
After your suggestion I discovered that my tiny shop is smaller than the lathe you suggest







There is not enough space!!

Thanks anyway

Petros


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## Bob Korves

petcnc said:


> After your suggestion I discovered that my tiny shop is smaller than the lathe you suggest
> There is not enough space!!
> Thanks anyway
> Petros


More than 1100 kg (2500 pounds) as well...


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## petcnc

Bob Korves said:


> More than 1100 kg (2500 pounds) as well...



That makes it slightly heavier than the one I have got.

Seriously now!

I don't know how can I lift it with my left hand to clean underneath it with my right hand and a paint brush

I might have to use compressed air, something many people in this forum would dissagree! 

Petros


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## CarlosA

petcnc said:


> There is not enough space!!



Nice shop ... that is about the size of my apartment machine shop.


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## petcnc

Convenient as well... everything is within reach of your hands!!!


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## Sk8ter

Looks real good petros! now...where is the bed flexing after the mod? you can add some concrete in the lathe bed webs this will stop any twist!..well i would only add about half way as you may need some twist to make it straight...

just a few thougths..I prob will do this to mine thanks for sharing...I too added a larger chuck a 6 3/8" diam one! 

Lawrence


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## Sk8ter

some thougths I have a 24"x24"x3" thick piece of granite surface plate  that I was thinking of drilling some holes to mount my little lathe too...

what you guys think?

Lawrence


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## petcnc

Sk8ter said:


> some thougths I have a 24"x24"x3" thick piece of granite surface plate  that I was thinking of drilling some holes to mount my little lathe too...
> 
> what you guys think?
> 
> Lawrence



Well... although very interesting thought, I think it is a ...misuse (to say the least)  of the surface plate to use it as a base for the lathe. Besides of its high cost, I should think that the base of your lathe is not meant to be bolted on a surface plate as it is not flat. You need either shims or to use bolts & nuts to adjust it. But this way you cancel the advantage of the surface plate: it's flatness.
I think you could do it if you machine the base of the lathe flat (and parallel to the bed ways) and then use the S/P as a base.

Petros


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## Andre

You could also fill the bed with cement or concrete. Just make sure you keep the level below the tailstock clamp.


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## petcnc

Sk8ter said:


> ...where is the bed flexing after the mod? you can add some concrete in the lathe bed webs this will stop any twist!..well i would only add about half way as you may need some twist to make it straight...
> Lawrence



Lawrence, 
Sorry but english is not my mother tongue and I'm not sure I can follow your question:
"where is the bed flexing after the mod?"
I was trying to eliminate the flexing in the first place!

As for the concrete you gave me the idea of filling it after eliminating any flex of the lathe bed to keep it that way for ever Ok not for ever but for a long-long time.

Petros


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## Sk8ter

all good Petros ...I was just curious as to the flexing now that the bed is not more inert....I just bolted per your idea! 2.... 1/4" thick pieces x 4" wide plates of 1045 steel together to span across one side to the other boss...I its an improvement...now to add some concrete  in between the webs...


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## petcnc

Lawrence did you measure flexibility before and after the mod as to have an idea of the plate's contribution to stifness of the lathe?
It would be interesting to have some flexibility data of the lathe in all 3 states: as is - with plates - with plates and concrete.

Petros


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## Sk8ter

Hello Petros, believe it or not I took your word for it...and we all know it flexes but no i didn't measure before after etc...

let me ask you so were both on the same page how did you measure the flex?

further i can tell how it sits there and while running esp with my huge chuck its more stable


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## petcnc

Lawrence hi
To measure flexibility just fix a bar  to the chuck, support the TDI to the toolpost move the carriage all the way towards the tailstock touch the bar with the TDI and zero it (see photo)
(edit) DO NOT support it at the tailstock end!






Now with your left hand hold headstock and with your right hand hold tailstock. Pull with one hand and push with the other while reading the measurement on TDI.
Reverse the push-pull procedure and note the new measurement.
In my case the measurement was  + 0.25 and -0.25 mm accordingly.
Needless to say that with  a bar that has the maximum length the lathe can handle, you will take the most accurate data.

Petros


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## Sk8ter

Ok update!:

I put a 1" dia mild steel bar drilled a center hole and moved the bar all the out..(tail stock is at the end of bed) put indicator in my tool post with left hand grabbed back to headstock right hand tail stock and i tried to twist..... could hardly  see it move maybe .0005"! ok good

now i turned down the bar to clean it up took a few passes then a few thou pass and measured less then.0005" taper from end to end but of an 8" cut lenght bar ....actually it was prob dead on but this steel is such quality (teary) just because of that i was getting a dead on reading and the .0005" difference....  ...this coincides with the .0005" twist or not!? I did not shim anything! I just bolted those 2..... 1/4"1045 steel plates on the bottom looks like this is an easy mod still portable and fun! I did have the tail stock center still in while while turn down the bar this could have influenced my reading but I doubt it.....no concrete needed!

Lawrence


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## petcnc

Well done then! Job done!
I think your lathe is solid as a rock! Is it a 7x12 lathe or bigger?


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## Sk8ter

its a micromark 7x16...I will do more tests its very hot out today!


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## petcnc

Although on the other side of the globe weather is similar here!


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## RJSakowski

petcnc said:


> Lawrence hi
> To measure flexibility just fix a bar in between centers, support the TDI to the toolpost move the carriage all the way towards the tailstock touch the bar with the TDI and zero it (see photo)
> 
> View attachment 130444
> 
> 
> Now with your left hand hold headstock and with your right hand hold tailstock. Pull with one hand and push with the other while reading the measurement on TDI.
> Reverse the push-pull procedure and note the new measurement.
> In my case the measurement was  + 0.25 and -0.25 mm accordingly.
> Needless to say that with  a bar that has the maximum length the lathe can handle, you will take the most accurate data.
> 
> Petros


Petros,  It would seem to me that to measure flexing of the lathe you would not want to constrain it with the tailstock center.  By doing so, the bar will follow the tailstock as does the bed twist.  The bar should be floating, secured only by the headstock chuck.  In that way, you will be measuring true flex relative to the headstock.

Using your method, I see flex of about .0002" on my G0602 when applying an estimated 100 lbs. of force to the tailstock.  With the bar floating, I see about 10x that flex.  Also, since you are measuring flex in the bed relative to the tailstock, I believe that the measurement will be the greatest about midway between the headstock and tailstock support.


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## Sk8ter

RJ is correct without the tailstock supporting the bar I get about 10thou


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## petcnc

Rj must be right,
It has been some time since I did the test on mine to recall all details!
Age does not come alone!!!
Sorry to mislead you Lawrence!

Petros
(Edit) RJ is wright as I did it this way initially! I desribed the procedure to may 1st post!!!


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## Sk8ter

all good petros, we live and learn and make mistakes! no one is an island


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## petcnc

Thank you Lawrence I have corrected the previous post that desribed the procedure!!

I have learned my lesson! Dont rush! recall all details before you make a fool of yourself

Petros


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## Sk8ter

Nah no fool sir....real good information ...your idea made me do mine.... although different in approach I like it...

now what to do I need a new belt for my micromark 7x16 its different then the regular 7x lathes


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## Sk8ter

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


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## petcnc

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


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## petcnc

Sk8ter said:


> 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



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


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## Sk8ter

petcnc said:


> 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


twist the bed and the results were +0.07 and - 0.08

you did mean .007" -.008" ?


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## Sk8ter

petcnc said:


> 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




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.


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## petcnc

Sk8ter said:


> twist the bed and the results were +0.07 and - 0.08
> 
> you did mean .007" -.008" ?



+0.07 mm -0.08mm total flex about 0.15mm


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## petcnc

Sk8ter said:


> ..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.



could'nt agree more on both

Petros


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## Sk8ter

petcnc said:


> +0.07 mm -0.08mm total flex about 0.15mm




.07mm! wow that's excellent!


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## petcnc

Sk8ter said:


> .07mm! wow that's excellent!


Take into consideration that it is a 7X12 mini lathe! Im' not sure that the base could be that stiff it was 7X16!


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## Downunder Bob

wrmiller said:


> 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


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## MSD0

Pretty cool project. I was thinking about doing something like this with my MicroMark 7x16, but there's so much flex in the cross slide and carriage it didn't seem worth it.


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## petcnc

MSD0 said:


> Pretty cool project. I was thinking about doing something like this with my MicroMark 7x16, but there's so much flex in the cross slide and carriage it didn't seem worth it.



MSDO, One thing at a time! 
Start with fixing all problems with cross slide and carriage and finish with lathe bed.
We all followed that same road!

Petros


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## petcnc

bobshobby said:


> 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



Bob, sometimes "bigger is not better". In my case I have to build a bigger shop to accomodate a bigger lathe!
As you can see my tiny shop is filled up to the ceiling!

Petros


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## wrmiller

petcnc said:


> Bob, sometimes "bigger is not better". In my case I have to build a bigger shop to accomodate a bigger lathe!
> As you can see my tiny shop is filled up to the ceiling!
> 
> Petros



Nice shop Petros! I had a similar one many years ago. My wife called it my "Rat's Nest". 

Yea that seems to be one of the most frequently used statements in this hobby. Sometimes, "bigger" just isn't desired or possible, for any number of reasons. A friend who makes parts for R/C cars and planes (and other small parts for his projects) just laughs when I tell him he needs a lathe like I have now, as he too doesn't have the space for one. Although, he as been quite happy with that modified 7x16 lathe I gave him. After we lapped in the saddle and cross slide's surfaces (and the tapered gibbs he made) the machine took on a whole new personality. Last I heard he made a new compound mount for it that really seemed to make a difference. Of course it doesn't perform like a larger, more rigid lathe, but it apparently works quite well for his current needs and shop limitations.


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## petcnc

wrmiller said:


> Nice shop Petros! I had a similar one many years ago. My wife called it my "Rat's Nest".
> 
> Yea that seems to be one of the most frequently used statements in this hobby. Sometimes, "bigger" just isn't desired or possible, for any number of reasons. A friend who makes parts for R/C cars and planes (and other small parts for his projects) just laughs when I tell him he needs a lathe like I have now, as he too doesn't have the space for one. Although, he as been quite happy with that modified 7x16 lathe I gave him. After we lapped in the saddle and cross slide's surfaces (and the tapered gibbs he made) the machine took on a whole new personality. Last I heard he made a new compound mount for it that really seemed to make a difference. Of course it doesn't perform like a larger, more rigid lathe, but it apparently works quite well for his current needs and shop limitations.



My wife calls it "Cave" as she does not know most of the things in there.

Petros


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## Sk8ter

I find the little my lathe 7x16 to machine most small stuff OK what it really does not like is interrupted cuts thats when you really can tell it flex's ....whats interesting is you can actually machine some stuff much faster then with a larger lathe....I have had several larger lathes ...my Hendey and colchester ...both large lathes....there is something nice about the little lathe its much more quiet for one...and will machine most round stuff pretty good...guys it has a lot to do with knowing your machine then if its bigger heavier etc...it just takes longer....I do like my little lathe its a sometimes love hate thing ...

Lawrence


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## Charles Spencer

petcnc said:


> 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!
> 
> Petros



Sounds correct.  Remember, the Greeks invented geometry.


Petros, I love the excellent use of space and organization of your shop.  I'll bet that you can get a lot done quickly with that set up.


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## petcnc

Charles Spencer said:


> Petros, I love the excellent use of space and organization of your shop.  I'll bet that you can get a lot done quickly with that set up.



Charles, thanks for the kind words! 
My shop makes two people a crowd.
Use of space: I think is ok
Organization: there is room for improvement!
A Funny thing is that every friend not associated with tools and machines (most of them) comes in, think my shop is a mess and they wonder how can I find anything in there!
To be honest, sometimes I wonder myself!

Petros


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## kevin.j.lovall

Billh50 said:


> Very interesting....Since I am going to be starting a bed extension on my mini-lathe maybe I will need something thicker than what I was going to use for the base. Will have to think about this for a bit. I will be posting pics as I go along. Right now I need to clean up both beds and check some dimensions. So far the dimensions I checked look good for the donor bed to work.



Sorry to hijack this thread but have you gotten your extension done yet? I'm planning on extending my bed of my 7x10 HF lathe with a donor bed and am looking for more info. 

Thanks,
Kevin


Sent from my iPhone using Tapatalk


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## Billh50

I haven't yet. Life has gotten in the way. I have only gotten as far as taking all dimensions from both my lathe and donor bed. They should match up height wise with just a slight bit of milling on the donor and adding a foot plate at the mounting end. I had to stop there as I had to go through my drill press because it wasn't milling too good. Still isn't perfect so I was hesitant to do any milling on the lathes. Then life got in the way. But will be getting back to it soon. ( I hope )


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## Downunder Bob

Billh50 said:


> I haven't yet. Life has gotten in the way. I have only gotten as far as taking all dimensions from both my lathe and donor bed. They should match up height wise with just a slight bit of milling on the donor and adding a foot plate at the mounting end. I had to stop there as I had to go through my drill press because it wasn't milling too good. Still isn't perfect so I was hesitant to do any milling on the lathes. Then life got in the way. But will be getting back to it soon. ( I hope )



I would suggest a stiffening frame be made as a box girder, a simple plate is way too flexible, and both beds aligned and firmly attached to it. If you can get you hands on a laser gun sight or something similar to align every thing up. The better you get this alignment the better the whole thing will be. Do you have any mates with some engineering skills that can help with the box girder?  Over design will be better than under design in this case.

And I'm thinking my desire to make and fit a vertical spindle mill head to a much larger and stiffer lathe is ambitious.

Good luck.


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## Billh50

Bob,
I appreciate your input. I was a special machine designer for 10 years and a machine builder for 5 years before that. So I picked up a bit of knowledge and feel I can do the job right with the proper equipment. I am only interested in making the lathe longer not add a milling head. Also I do not plan on over designing to the point of making this become a major change as it would then be better to just get a larger lathe. My goal is to make it a workable longer lathe with as little expenditure as possible.


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## Downunder Bob

Billh50 said:


> Bob,
> I appreciate your input. I was a special machine designer for 10 years and a machine builder for 5 years before that. So I picked up a bit of knowledge and feel I can do the job right with the proper equipment. I am only interested in making the lathe longer not add a milling head. Also I do not plan on over designing to the point of making this become a major change as it would then be better to just get a larger lathe. My goal is to make it a workable longer lathe with as little expenditure as possible.



Obviously you don't need any advice, I didn't realise you had that experience I thought you were looking for advice. However if you have that training, can you please advise me how to build a vertical spindle mill attachment for a 12" x 16" lathe, I think I've got the fame worked out, but would appreciate some advice on building the spindle._._


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## Billh50

Do you just need advice on the spindle itself or the whole project ?
There are a few things to consider for the spindle. Like what type of collet system you want to use. amount of travel for the Quill. Speeds to run at. What machines and equipment you have to work with. Exactly what make and model of machine you wish to mount this to.


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## Downunder Bob

Billh50 said:


> Do you just need advice on the spindle itself or the whole project ?
> There are a few things to consider for the spindle. Like what type of collet system you want to use. amount of travel for the Quill. Speeds to run at. What machines and equipment you have to work with. Exactly what make and model of machine you wish to mount this to.



Thanks for your reply Bill, Sorry for the delay in getting back to you, but I've been away for a few days.

The lathe I intend to mount the milling spindle on is a Liang Dei LD 1216 GH. this is a Taiwanese made machine. The local distributor here in Australia assures me they are very good quality, they claim to have just supplied half a dozen of them to their local trade school in Melbourne, I'm about 500 m. west of there in Adelaide. I'm hoping to have my new lathe delivered in about a month.The only other tools I have is a 7"and 5"angle grinders, a couple of cordless drills, a very cheap and poor quality chinese bench mount drill press, barely able to drill a decent hole let alone any milling.

This lathe is rather short for it's size because I don't have much room, and certainly none for any other machines, so I'm going to have to do everything on it, hence the desire to make a vertical spindle milling attachment. The cast iron bed is quite solid 190 mm (7.5"wide) with good depth.  

The cross slide has a power feed travel of 170 mm 6.75".  The compound slide has a travel of 90 mm 3.5" if I need to use although I prefer not too , as I feel it will compromise rigidity.

It is my intention to make a strong plate that will clamp to the bed in a similar way to the tailstock with a sturdy column welded on it, this will support the spindle which will extend out over the cross slide about 6" from the column.  The mounting plate will have a "V"groove to locate on the front V of the bed and a foot to fit on the rear flat of the bed, this should give it stability and location. 

The spindle will locate on the column by bolting two plates (say 6 mm thick) together on is welded to the column and the other will be welded to the outer part of the spindle assembly. this will allow me to adjust the height of the spindle collet. above the cross slide, from 4"to 12"in 4 " steps, I'm thinking of using ER 20 collet system. The collets will be held in the spindle by a conventional draw bar.

The spindle assembly itself I'm thinking along the lines of using a 90 x 100 mm steel tube with a 80 x 90 tube machined to fit inside it. The inner tube will have a roller bearing for radial forces and a taper roller for axial forces at the collet end and a ball bearing at the top end. The spindle will run in these bearings. The top end of the spindle will have a spline to carry a pulley for a belt drive from the lathe main shaft, and by using a 2:1 step up I'll have 12 speeds from 140 to 3000 RPM. Obliviously I will, need different belt lengths when changing the set height of the head. 

The inner tube will have a rack cut in it to mesh with a pinion on the height adjustment for the spindle, I'll also have a slot to take a length of key steel to fit in a matching slot on the outer tube. The slot in the outer tube will go right through so that with a clamping screw I can adjust the tightness on the inner tube.

I would appreciate any advice on the project particularly if you think I'm heading in the wrong direction.

Thanks again,

Bob.


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## Billh50

I can somewhat visualize what you are attempting. It should work for light milling. But you might have trouble getting anything square enough to holding any close tolerances.


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## Downunder Bob

Billh50 said:


> I can somewhat visualize what you are attempting. It should work for light milling. But you might have trouble getting anything square enough to holding any close tolerances.



Thanks Bill,

I realise that I will have to take light cuts as with all milling on a lathe. As a special machine designer do you see any parts of my concept that I could consider doing in a better way, please advise.

Bob.


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## Billh50

As long as it is built strong enough and clamps down tight enough I see no problem.


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## Downunder Bob

Billh50 said:


> As long as it is built strong enough and clamps down tight enough I see no problem.



That's the plan build it strong and rigid and clamp tight to bed.

I hope to start building it in about a month when I'm expecting my new lathe to be delivered, I will post photos.


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