Building your own lathe that works

[tool-me-up]

Ok, this thread will explain how i built my lathe, i know you all like piccies but once i get busy i forget to keep picking up the camera

To start with you need a solid base with two uprights on it, and further upright on the back of the rear upright. I used 6" steel girder, with a 10mm base and 12 mm legs. Nice and solid

As you can see i have already mounted my motor to the side of the bed, and i have ground out ( quite scruffily) slots for the spindle to sit in - i was not going to try and drill two 30mm holes precisely in this stuff!!

Next is to attach the spindle - i picked 30mm ID 55mm OD bearings that are part of a transit van driveline ( the differential i think) so they should stand up to a few 1000rpm and sideways loads.
I used 1/2 thick aluminium plate to mount them in - you could use a hole saw for this but as i made the holes too small, i had to finish boring them out on a mates lathe.

the bearing should just about drop through the hole - you dont want a tight fit.
Next we drill two holes down the sides of the bearing hole making sure to go well past the halfway mark ( half the diameter of the bearing hole). then hacksaw the mounts in half leaving you with a big plate with a U on top and a small plate with a U on the bottom.
Drill out the holes in the small plate so your chosen bolts can pass through and drill the bottom plate a bit deeper then tap for your chosen bolts

As you can see there is a slot in this plate and there should also be a slot in the other plate but running in the opposite direction. Hold the bottom part of the mount onto the support ( of the lathe ) and drop the spindle on top, and eye up roughly where it needs to be and mark the centre of the slot in the support for drilling. Do this either end and drill them to take bolts - i used M8.

Now bolt on both the mounts via the slots and nip them tight-ish you will be shuffling them round with a hammer in a minute

pop your spindle in and tighten down the top parts of the mounts so its nice and solid, put some thing in the chuck and centre it using a run out gauge ( if you have a three jaw you will just have to trust it is straight)

pop your slides or carriage way ( cross vice for me ) where they should go - roughly aligned with the spindle

now you start levelling the spindle out using digital vernier and a small engineers set square measure the distance between the bottom rail ( this is important that you measure the bottom rail and not part of the frame etc, the spindle wants to be level with the ground surface that the tool post slides SIDEWAYS on)
Adjust the spindle mount by tapping with a hammer until you are sure it is very close to being perfectly level.
once it is level look at it from above and make sure it runs parallel to the cross slides. I attached G-clamps to my mounts to stop them moving then drilled another four 8mm holes through the mounts and the steel, and fastened it in with M8 bolts, your spindle should now be rock solid in place.

Now you have to align the cross slides with the spindle, i did this by tapping 6 x M6 bolts into the bed and then nipping the cross slide up.
take a very small and slow cut of your test peice about two inches long and measure each end, you then tap the crosslide with a hammer until it is sat straight with the test peice and do another cut to check.
I have got mine to 0.03 over two inches but its not finished yet so i will true that up later - if i can!

Now double check your height measurements just in-case its moved whilst drilling, bolting etc, if it has moved and your spindle is already bolted securely you can use shims under the slides to level it back off.

Once you are happy its all done tighten the crosslide down as good as you can - if its not cast iron like mine weld the pipper down!

Finally just for helijohn, pour over a tin of hammerite, do not attempt to brush it on neatly this is not how helijohn likes it - just dip your brush in an slap it on

have fun......

There is seperate threads for gearing properly and tool post design

 

[twothumbs]

This is a great thread. I will need to read it through very carefully and come back on it. Also look at your other threads. Thanks and best wishes.

 

[Green]

Very good. I've been thinking about building a big bowl turning lathe. Just need to find some steel that's heavy enough.

 

[tool-me-up]

Built this a couple of years ago, for turning metal, its still in use now ( just not as often )
The trick seems to be getting the head section and bed to stay rigid with each other.

Depending on how tall and long the lathe needs to be a wood lathe should work well with something a bit thinner as its not under as much stress. My first attempts at a lathe were actually from a wood lathe and while it would do fine cuts in alloys ( so i assume it would be ok for wood) it was the steel it struggled with.

If you do build your own I highly recommend getting a 3 phase motor set-up.

I have just aquired a 3/4HP motor and programmable controller for modification onto a cheap pillar drill ( maybe later on today ) and the functions they add are well worth the investment.

For example when you hit go on a single phase motor - it goes - straight to top speed.

On the 3 phase controller i can set a speed in % so i can pick 50-100% speed or any other value i choose, hit go, and it will steadily accelerate to this speed over a length of time that i pre-programme in.

Can also add emergency stops, jog modes, braking modes, on-the-fly speed control, RPM control ( auto ramps ups voltage to maintain shaft speed under load - must have sensor fitted ) via a 24vdc system built in to the unit.
Much more useful on things like lathes than pillar drills but I got it giveaway so i wasnt fussy about it not been used to its potential.

Also I understand that watt for watt 3 phase motors have a lot more torque than an standard single phase motor.

 

[tool-me-up]

http://www.ebay.co.uk/itm/4ft-wood-turn ... 35d0b5f5fd
http://www.ebay.co.uk/itm/Myford-ML8-Wo ... 1e856254f2

looking at the above lathes you could probably use a section of scaffolding pipe as the bed - or better still use three in a triange, with a fixed headstock and either a fixed tailstock or just fix the tail end to a plate of steel and have a traveling tail on the upper rail.

You could get away with ally, for the tail stock mounts and make the hole for the tube to pass through with a hole-saw - then you can drill and tap a couple of large bolts into it so you can lock it to the rail.

Personally I would buy a cheap bolt-on tailstock and just make mounts for it just to save a bit of a head ache.

As a wood lathe doesnt have to be as accurate as a metal lathe then to line every thing up I would use a hollow spindle for the head stock - and push a STRAIGHT peice of tubing through it that is is a good fit so it stays straight and doesnt sit inside the spindle at an angle and this will give you a close reference for where the tail stock needs to be centered.

Might be a bit easier than squares and micrometers - especially as the bed will be much longer than the one i built.

 

[AndyT]

The difference between wood lathes and metalworking lathes (since about 1875) is that in the metal lathe the shape of the finished work is governed by the shape of the bed as the tool carriage moves along it whereas in a wood lathe straightness of work is controlled by the shape of the toolrest and how the operator guides the tool along it. So although scaffold poles would be fine for a wood lathe they would be frustratingly inaccurate for a metal lathe.

 

[Green]

I'm thinking about making a heavy lathe using large section steel H beams and ruddy great pillow blocks. It will be a dedicated bowl lathe so the bed will be very short compared to normal wood lathes. Variable speed would be nice. Still at the fag packet stage though...

 

[wizard]

The metal lathe is to turn between centres that machine is not fit for turning and an accident waiting to happen. :roll:

 

[monkeybiter]

The metal lathe is to turn between centres that machine is not fit for turning and an accident waiting to happen. :roll:

Not done much on a metalwork lathe then?

 

[tool-me-up]

The metal lathe is to turn between centres that machine is not fit for turning and an accident waiting to happen. :roll:

Look at dates on pics, I still use it now....Have made hundreds of things with it, no accidents...

heres just a few that i used to make repeatedly to a fair accuracy for use on air rifles.

 

[wizard]

Ok for short bits of soft metal maybe but i would not encourage other people to do it. this is a small cheap lathe

 

[tool-me-up]

If you built one the same as mine you can only machine around 5" at a time anyways because the slide on the bed is so short.