[kong]

Hiya guys, following on from this thread, I am going to attempt to make the auto lathe turret as found over here.
I am following the plans that are available on the mach2 yahoo site, but will email the original author to see if he will allow me to post the drawings here.

So then, to start with, I have purchased a 6"x6"x4" block of cast iron for the body. It weighs around 20-25 pounds, and currently have it chucked on the lathe. I have got as far as facing one side, drilling through, and boring the two holes for the indexing spindle to ride in. As a slight change to the plans, I have bored the bearing hole 1/2" oversize, and I intend to sleeve it with phospor bronze. This is where I am at now....

[JFettig]

Kong, looks like an awesome project. Do you have any drawings or design plans you are going off of? I am still getting ideas, maybe some day I will build one, more likely if I was to get a bigger lathe.

Jon

[kong]

Hi Jon, I am using the plans available from the Mach2 yahoo group files section. Hell, I am even working in imperial measurements! That cast iron is not nice to machine, just figured it would all add to the rigidity of the thing. Just having a break for tea, then I will hopefully get the main piston cylinder bored out.

[DieGuy]

Hell, I am even working in imperial measurements! That cast iron is not nice to machine, just figured it would all add to the rigidity of the thing.

I hear you about the cast iron, When I served my tool and die apprenticship (many moons ago) we broke a cast iron connecting rod in our 80 ton press. Guess who got the job of making the new one out a block of cast iron about 24 X 16 X 8. Nasty stuff.

[Mcgyver]

kong, cast iron's dampening and dimension stability make it right choice and as you've found it usually works best when machined in imperial units, but what’s going on with the cutting problem? aside from being a pain to clean up, I've always found good CI the nicest of material to machine, once you break through the outer skin that is. Machines easily, easy to get a nice finish, no stringy chips, no messy coolant or oil etc.

[MIKE JEFFERS]

kong
mcgyver's right cast iron should cut nice when through the skin
i used to make gravity dies from the stuff, if all you've cut before is ali or m/s
you'll find it a bit different but hopefully satisfying (eventually)
mind you the wife will start moaning when you enter the house looking like a miner
(...or maybe not..;-} )
by the way DON'T USE COOLANT ....low revs and a "brisk" feed.
finally there's something about the imperial unit thing .
maybe it's just me.
mike

[kong]

Lol guys, I am in the UK, and hence always use metric measurements! I can honestly say I have never machined anything to imperial measurements before!
Don't get me wrong on the cast iron, it is just that I am not setup for this large a piece, I am boring a 4" diameter hole, 3" deep into the iron with a 3/4" boring bar. This is why it is hard work! I usualy machine aluminium with bores upto 2.5", so that is what I am setup for.
I suppose I should do a quick update - the machining is slow on the iron for reasons mentioned above, hoepfully I will get that finnished off this evening. Just got back from the scrap yard on the lookout for bronze or brass for the piston - 4" dia, 1.5" long. Everything there was too big, and since they don't cut it, I would have ended up paying £22 for the closest size piece ($45). I will go look again on Monday. I will get some pictures up of my progress later on tonight

[kong]

Good, that is the boring bit done, boring, eh, eh?!
Nevermind, I will go back to work!

[Bloy2004]

Nice Kong,
heh...now I get to watch you!

[DieGuy]

I am watching this project with baited breath.

[kong]

Right then, next part! I have made two aluminium plates, bored one to accept a stepper-motor shaft, and have pressed dowel-pins at 4 points around the circumference. The second plate is the same size, and bored 10mm so it can be bolted to the main spindle. It also has holes around the edge, but these are slightly large so it can slide on the dowels.
When the turret is in the locked position, the two plates will be (almost) pressed together. When it is unlocked, the piston will push the spindle forwards, therefore pulling the "floating" plate with it. The dowels will keep the stepper motor connected to this floating plate, and will still be able to turn the main spindle. At the moment, they slide perfectly, but when I get everything assembled, there will probably be some binding. If this is the case, I will have to slot the holes slightly, being careful not to introduce backlash into the system.

Clear as mud eh?!

[MIKE JEFFERS]

looking good
mike

[kong]

Good news, the author of theplans has allowed me to put them up for download.
So it is a big thankyou to Ron Kliewer of Vancouver b.c

[kong]

I got to the scrapyard again today, picked up a nice piece of stainless for the spindle, and a big block of brass for the piston. I only managed to make the spindle today though, and was pleasantly suprised to see it machined quite easily on the lathe. Using speeds and feeds similar to aluminium, I managed to get a quality surface finnish.
Here's a couple of shots to close

[JFettig]

Kong, I am redesigning these in 4" diameter turret for my mini lathe, I am assuming the piston is the part that goes on the larger part of that spindle. Do you know what the reason for it being able to slide is? it slides on the spindle. I am trying to decide how I want to do this and it depends on if this thing needs to slide or not.

Your progress is looking great. I am looking forward to possibly making a 4" turret for myself sometime or another.

Jon

[kong]

Hi Jon, to be honest, I don't know! It only slides around 0.15", so I am guessing the author was just trying to maximise the amount of air used to actuate the assembly. I would say fixed would be fine. I think that brings up one point though, which I know nothing about - how will the reduced air volume inside your smaller cylinder affect it's clamping pressure?
Since you are in design mode, I would also be interested in your ideas for the main tooling plate. I am looking for a method to adjust the centre height of the tools, and also I would like to be able to have "bolt-on" boring bar holders. I am thinking octagonal plate here. Have you got that far yet?

[JFettig]

What I would do if I had more room is mount the turret in the back position, this way you can run the tools upsidedown and always have the same tip height. Because I dont have room for it right now, I will put mine infront.
If I went with a bigger face, I would offset the tools down a little, basicly so the tip is at or below the centerline of the tooling plate.

The Dorian tool manual tool turrets have bolt on things that bolt onto the end of the octagon for boring bars and drills and stuff. I was thinking about doing something like this too, the main problem here is that if you have the bar sticking out the back, you cant rotate all the way around.

This is also similar on the auto tool turret on the powerpath 15 we have at work too, their are tool holders that bolt to the end of the faces similar to the boring tools on the dorian tool turret but are on the face of the turret, the boring holders bolt on the end too.

Jon

[argon5w]

The volume of the cylinder shouldn't make a difference on clamping force. Your primary concern with a cylinder is the surface area of the inside face. The volume will make a difference if you have a limited air supply or a very small compressor with no tank.

Richard
www.homemachineshop.com

[kong]

More stuff! I made the piston today, lovely fit. Even without the O-ring installed, I can hear a little "puff" of air if I move the piston within the cylinder. I will go to the steel shop tomorrow and pick up the main tooling plate.7" diameter I reckon, and I will turn it into an octagon. Should work

[ty1295]

I would think about making the octagon plate bolt on to a second plate hooked to the piston.

Then slot the holes on octagon plate where it bolts to master. You can then adjust center height later.

This is how most turret's are built on full cnc equipment.