Mini lathe transmission replacement

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ketanswali:
loply,
You might want to check if your control board has overload protection. The nylon gears are indeed there as a fail safe. Yes they are economical. Usually, the idea is that they break instead of blowing your control board, but sometimes it is a toss-up between which will go - the nylon gear, or the board, or both at the same time. The design is such that it should break the gears first. The control board to be found in C2 or C2 type mini-lathes do not have overload protection.

So if you put in metal gears in mini-lathes which do not have overload protection, you have to be more careful when using the machine, because the nylon gear fail safe is now gone, so probability of blowing the board has now increased. Over torquing taper roller bearings on such machines (without overload protection), can also have a small risk of blowing the control board if the motor needs to draw more power to allow the spindle to turn.

The probablility of blowing the board are reduced if you have a C3 / C3 type mini-lathe which have overload protection, however it does not mean that the risk is totally removed.

mini-lathes are built to a price, a price at which it makes it possible for more people to enter the hobby, so yes, there are compromises made too.

Davo J:
Hi Rich,
I thought this forum was called Mad Modder for a reason. Or should it be change it to Cautious Modder, :lol:
I have been reading your posts and as you say it's the journey and the learning thats fun, thats what this hobby is all about and keeps us coming back for more.
There are a lot of us in your shoes, where we have to work with what we have and cant afford anything bigger, or don't have the room.
Keep posting your mods, as some of us are interested and are reading it, even if we don't reply sometimes.
:nrocks:

Dave

PekkaNF:

--- Quote from: Davo J on June 07, 2011, 05:02:02 AM ---Hi Rich,
I thought this forum was called Mad Modder for a reason. Or should it be change it to Cautious Modder, :lol:
--- End quote ---

Dave I had long time a go a physics teacher and an avid leisure pilot who said: "There are only two kind of pilots: young-an-brave; and old-an-cautious" Then he always made a very sad face.

I apreciate Ketans input here, I'm damn sure he knows what he is talking about.

Pekka the flack magnet

John Stevenson:
I fully agree not to overload the original drives or motor and controls.

However if you do need the *extra* bit of power and drive for the odd job there are ways round this.

This setup allows me to use the whole of the 7.5 Hp from the big TOS lathe onto the C0 without any fear of blowing a driver board. :poke: :lol:

John S.

picclock:
OK, there are a few points that should be mentioned here, which seem to be being ignored.

Assuming a constant tool cutting speed the work that the lathe doesn't vary (much) with the diameter of the work. So whether your turning a 1" piece of steel or a 5" piece of steel at 50fpm, assuming the depth of cut is the same the work done is the same. So the power required to do the cutting is the same.

But, obviously the 5" diameter piece of steel is being turned at 1/5th of the speed. Consequently the spindle and final drive gears are subjected to 5x the torque of the 1" piece. The bending force on the cross slide / compound is increased but the turning force on the lathe bed remains the same.

So provided the spindle, gear train and cross slide are up to the increased forces then there really isn't a problem. On the 7x12 minilathe forum there are many members who have modded there lathe in this way and have good experiences. I am one of them.

In order to increase the torque from the std motor to allow turning larger diameters most people use a layshaft with additional gears.

@ Loply
Don't be discouraged. The plastic gears can disintegrate for lots of reasons. It may be that the lever that engages them is indexed incorrectly and only partly meshed the teeth sometimes. I've never had a problem with 60mm Aluminium (apart from the price :lol:), even before my machine was modded.

@ John Stevenson
Laughed my socks off - your lucky to have such a large lathe to work with. A lot of people, myself included, simply don't have the room or finance for such a luxury. But that's when the creativity (hopefully) kicks in.

Best Regards

picclock

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