Thread: Chris's 2nd Build "Big K4huna"

Went and got replacement parts for my lathe, the Lathe is 2MT not 3MT as in the specs, the guy there even rang up someone to fix up the site.

Not too worried about it, got some 24mm shaft today and was playing with the lathe, I dont have a clue how the parting tool works as I broke one of the 2 cutting bits supplied, just decided to dump it and I will just use a hacksaw.

Got a clamping kit also for the mill so I can start milling that aluminium, should get time tommorow so hoping it all goes good.


BTW with the lathed bits do you use sandpaper once you have the final diameter to make it all smooth?

Originally Posted by Ch4iS

I think its the other way around being too big for the tailstock. I understand the big dead center now going into the headstock and the smaller going into the tailstock but the drill and live center seem to be a size in the middle of the 2.

I'll have to go back if this is the case I just want to make sure I am right in that I was given the wrong sizes.

Hi Chris,
I am not a machining expert by any means but from my trade training days I do remember part finish is a product of tool shape and cutting edge finish on the tool and feed rates and cutting depth.

So in summary and this is only IMHO and very general, high RPM very slow feed rates and very small cut depth on the finishing cuts and coolant if the tooling and material being machined requires it. Also for mild steel and cast iron tungsten carbide tooling with nice rounded cutting edge should give a nice finish.

Please remember I am drawing on memories from 27 years ago so it is not as sharp as it once was and tooling and techniques have probably moved on since then.

Cheers
Steve

Hi Chris,
Steve is on the ball there. To add to it the material you are working with is probably mild steel so don't expect a shinny finsh unless you do use emery or wet and dry.
Rather than finishing to size, machine to close fit but oversize and then hit it with emery. In effect you create a very fine thread with a lathe so hitting it with emery can knock off the high spots and reduce your diameter. You will learn by practise so give it a go and modify your technique to get the result you want.

Parting off is probably the hardest thing to do on a lathe. Leave it for the moment and once you understand and get to know your lathe then tackle it - not cheating if you hacksaw in the interim.

Learn how to measure accurately and then how to tranfer that to the dials on your lathe. Remember you measure in diameter and your cut on radius so half variation between diameter and finsihed size required.

Main thing is to have fun and don't worry if the scap bin gets used a bit as you learn.
I love working on the lathe but it did take a while to learn how to use it.

The lathe is actually fun to use unlike the Mill right now

First problem is, that 25mm is a pain in the #### to cut.

Next Problem was trying to figure out how the clamping kit works, I just ended up doing it like in the picture.

Next problem was the 2nd pass I did the 1/4" 2 flute just snapped on me, they seem very brittle, I snapped 2 all up and I now know how deep I can cut.

I was planning to just mill a rectangle, then draw where the holes need to be and drill them, as there is backlash in the X axis and a little in the Y axis.




Some pictures

Its actually ~24.65mm thick so I will probbally mill ~.3mm off each side.

Hi Chris,
Spend heaps of time setting up and think about what you want to do so there are less clamp movements. When you have finished one side set up another set of clamps then remove the first clamps if they are in the way. Don't undo any clamps until you have put alternative clamps on otherwise you loose your references.

See photo on how to use the clamps. Note bar is sloping down to job and tee nut and stud are positioned close to the job. Job is lifted off the table to allow for through cut.
I am not an expert and self taught so somebody chime in if the setup is wrong.

Look like you could use a bit of lubricant while you are cutting. A 1/4 inch carbide will snap easily though.
I would use a 1/2 inch high speed steel for a job like that. Less deflection on the thick sides.

Keep at it you will get it soon enough. Put on your favourite music unless it is head banging stuff and relax that way you won't be tempted to push it too hard.

What sort of depth should I be cutting at on each pass?

Would it be best to setup a pump and coolant? I have some spare coolant and I can get hoses and a pump from bunnings (Which isnt open tommorow I think )

BTW thanks for the picture rod I was baffled as to how the clamps were spose to go together.

Maybe up to 1mm per pass but 0.5mm per pass is safer.
Highest speed on the motor.
Just use WD40 or CRC. Kerosene is fine also.
You don't need to flood it you just need a little lubricant squirted or brushed on every so often.
Sorry rushing as I have to go out.
.

The Manual mill was killing me so I setup my cnc router and it seemed to handle the Aluminium without a issue at .5mm using the wood router bit not sure what you call it but it has the tungsten cutters on it, its not as brittle as the other router bit I have here.

I just drilled 10mm holes on my table and used the mill clamps to hold the aluminium in place.

Just had a few problems, limited to 500 lines so ill have to upgrade mach 3 tommorow, also had a wierd thing, it cut about .5mm off in one section, it wasnt missed steps as it kept doing it, checked my files and it isnt on there, do you get errors in the code sometimes?

Slowly working on my cnc router still but just wanted to point out.


When talking with One Steel they said they now have some el cheapo steel.

Basically I was told its made the same way as the other stuff, but it does not have some testing done on it so some businesses cannot use it as australia has strict guidelines on the steel or something when it comes to its use.

Got 4 lengths of 75x75x3mmx6000mm for $80 + GST each.

They are spose to stock all the standard sizes 100x100, 40x40 ect I think. They dont stock the 125x75 that I would use but oh well as I was told thats an australian size

Just thought id mention it as its quite a big difference in price, my local steel mob a reseller of one steel charges ~ $225 for the 8 meter lengths of tested steel, so its about a 50% saving.

Finally picked up a face mill attachment from hare and forbes + a big so called quality vice (weighs 27KG on its own with 6" width), and picked up a quality digital caliper from bunnings.

I got the block to 63.3mm wide +/- .05mm, It is perfect one side (The side I was measuring) but out by about .04mm on the other side.

3rd picture was the first time I milled one of the sides flat, I wasnt locking the Z axis "Doh" .04mm but its so small it wont matter for this part.

BTW I love the finish , no lubrication needed.

It will take time but I recon I can do things this way to get my mounts made

I will probbaly knock .33mm off each side to make it a even thickness of 24mm as its 24.66 right now.

Is the aluminium painted black or just dirty?


Should hopefully get all tommorow to do some work and then have a piece of aluminium with holes in it mounted to the linear bearings.

It's fun milling.
Hard to say if it is painted but it looks like it to me. Try a scotch bright on the surface and if it flakes off chances are it is paint.
Aluminum looks a lot worse in a photo than it actually is due to the camera flash.
You could face it if you wanted to but you have to be careful on the set up. A dial gauge comes in handy to set up jobs. Mount it on your mill head with a magnetic base and dial across your job to set it to zero.
A tip with those vises is to lightly tap with a soft faced hammer downwards on the job i.e. towards the bottom of the vice as you tighen the job in the jaws. They tend to lift the job as you tighten so this counteracts this movement. Heavy taps will make it bounce so light but firm taps - sounds a bit contradictory but you will get a feel for it.
A hammer is great for positioning a job as well - you have much more control tapping with a hammer than trying to shift it by hand.
One thing about machining is it usually takes longer to mount the job than to machine it so don't be in a hurry to turn on the switch.

Did the other piece, it might be a simple rectangle but it takes forever.

The idea is to cut the piece just larger than what you need so you dont need to do too many deep passes.

The 2nd one was perfect but the stupid Z axis dropped on me slightly.

Ended up with 63.15 but it is still usable, I can just recut it when I am able to. Length is 170.05mm

Hardest part I think will be the slot on the sides, still trying to figure out how to pull it off.

+ a pic of the slab I cut off for the sides, ~300x250

Hi Chris,
Coming along nicely.
Personally I would have the vice mounted through 90 degree on what you have.
Yeah got to remember to lock down the Z axis before cutting as well as the jib locks on the dovetail. It all a learning curve.
For cutting the slot clamp you piece to the table and maybe use a piece of angle iron clamped to your table as a guide for your material - helps get both slots in the exact position. Dial in an edge or the angle iron guide parallel to the slot making sure you have enough travel in you axis to cut the slot. Use a slot drill (2 flute end mill) secured in a collet chuck (never a drill chuck) and start cutting away.
You have a fair bit of time invested in this job so try on a piece of scrap first and when you do the real job take your time setting up and making sure everything is clamped down before cutting.
What did you clean the plate with and was it paint or dirt?

Originally Posted by rodm

What did you clean the plate with and was it paint or dirt?

Paint I think, but I dont understand why it would have been painted as aluminium in this day and age doesnt rust or is extremely hard to rust.

Just some water and detergent + a little effort with the sponge, then a bath in kero and dried off. I washed it so I could draw on it with a lead pencil.


I just had the vice that way as I was only doing the smaller pieces, I will need to mount it the other way to make a perfect rectange of 265x235 I think it is. the piece will need to be cut down slightly so it can fit under the cutter.

Is that the type of vise you were thinking raises the workpiece? should I still be tapping it with the hammer?


BTW that last picture is of the aluminium mounted in the vise and the cutter cutting about 200mm from the vise, it didnt vibrate much and had a nice clean cut but I wouldnt want to do deep cuts.