[davidtye23]

So far, so good.

[neilw20]

It is not even overtravel. Turn off the power with it stopped, and it will go down with no assistance, whatsoever, once you have it working nicely.

[handlewanker]

Hi Neil, could that be a case if the gibs are too loose to promote easy travel and no missed steps......I notice you mention "head nod", or grandma's syndrome....LOL......that would only happen if the gibs were slack and the head was hanging against slides and able to rock back and forth against the dovetails.

With an overhung weight like that I imagine it would be difficult to decide when the dovetails are bearing all the way and so fairly snug (tight), and when they are only bearing at the bottom and so just riding against the bottom of the dovetails.

You could only test this by having a test bar in the spindle/chuck and running the bar against a dial indicator while traveling up and down.

If the bar shows any leaning at the bottom towards the column, the dovetails are slack at the top due to the hung over weight.

Apart from a head load compensator for up and down travel you would also need a fixed counterbalance weight at the back to bring the centre of the head load to the centre of the Z axis screw, otherwise you're constantly driving up and down at an angle which will do the head dovetails not a lot of good.

This is a factor to be lived with as the design was not intended to have slack gibs for Z axis drive on the column......all column mills suffer from this problem.

The only way to completely overcome it would be to machine the dovetails off completely and fit large Hiwin type linear rails, and once you start that you might as well do the other dovetails too, but that would only happen in the super deluxe kit....LOL.

On my Ajax knee mill (manual) I had some shudder on the knee fast down travel when I first got the machine and I traced it to a looser than ideal gib on the knee.

The machine weighs 1 1/2 tons and the knee is quite a substantial part of that, having an internal gearbox for all travels and fast feeds etc.
Ian.

[mrpackethead]

Electronics;



Left over bits



X,Y and Z axis on now



Some modificaitons are needed to make the back cover fit back on.

[handlewanker]

Hi, you have been busy....one question, why do you need to keep all the manual parts on the machine that drive the quill if you're driving the Z axis from the column dovetails?

Those parts are weight in the head which you don't need......even the drive train should be a two pulley belt drive with a VFD.

I would think that once the quill is locked up, semi permanently, while the column is the Z axis drive path, all the unnecessary parts could be taken off, (and carefully stored).
Ian.

[mrpackethead]

Hi, you have been busy....one question, why do you need to keep all the manual parts on the machine that drive the quill if you're driving the Z axis from the column dovetails?

Those parts are weight in the head which you don't need......even the drive train should be a two pulley belt drive with a VFD.

I would think that once the quill is locked up, semi permanently, while the column is the Z axis drive path, all the unnecessary parts could be taken off, (and carefully stored).
Ian.

It is a good question.. And not one i'd thought of at all.. Leaving it on, does mean i can still use the machine as a boring old manual drill press when i need to..

for my application, Z axis accuracy is not that critical. I'm essentially making holes in alloy boxes.

[handlewanker]

Hi, that would be logical.......no unnecessary work etc, and you might want to just do a bit of manual drilling when the occasion arises.

For anyone wanting to go down the full CNC path I think this would have to be a consideration....I was horrified when the "head nod" syndrome was highlighted.

I could not imagine how you could bore a hole and on withdrawal have the head nodding all the way back out of the bore.

Due to the fact that the bite from the CNC bug is without any known cure, I have a similar project like the one you are currently working on, and that is a feasibility study for the conversion of a small table top type jig borer/mill to go to CNC capability.......a feasibility study means pencil and lots of paper for sketches and idea exploration, but as I have a graphics pad that is one file and lots of pen/stylus work.

When the "head nod" syndrome on column mill conversion was highlighted that immediately knocked out any thought of using the column dovetails on my borer for Z axis travel, and to overcome that I am going to add a full length 20mm thick "plate" to the column face to create a false front, attached to the existing dovetails and add Hiwin type rails for the Z axis travel, otherwise the dovetails would have to be milled off to give a flat mounting base for the rails and that is sheer butchery.
Ian.

[mrpackethead]

I've had a think about this, as well.. I'm pretty sure that for the requirment i'm looking at, i'll be just fine.. ( we tend to overdrill holes by .5mm or so anyway, they are never super tight fits.. ).. But.. I think its not unrelisitic to look to add a motor onto the quill drive. then the head can be drive to height, locked, and let the quill do the control.

[neilw20]

Mrpackethead!!!

Don't you dare take off the handle and stuff off the quill.
It makes the machine.
Move head to where you want zero to be.
Zero the DRO.
Move quill down to touch the job,
Lock the quill (only if you have no head nod)
Set zero on the DRO on the head.
Move the head up a bit.
Zero is now set to within microns.
No probe needed.
And it takes 15 seconds to do.

The machine is still a perfectly manageable manual machine.
I park in a convenient spot, and often just turn on the machine (no PC) to manually drill holes.

Using the quill you can position over a hole and tap holes by feel, quite well.
Position to next hole, and tap another, etc.

Bottom line.
Don't kill the quill!!

I am going to motorize the front knob with a removable drive mechanism.
Then it becomes a CNC EDM machine, running straight from Mach3.

Bottom line.
Don't kill the quill!!

Bottom line.
Don't kill the quill!!

Bottom line.
Don't kill the quill!!

Bottom line.
Don't kill the quill!!

and my machine has done over 2000 hours

[mrpackethead]

Mrpackethead!!!

Don't you dare take off the handle and stuff off the quill.

Ok, Ok, keep your hat on.. I'll leave it on: And i had no plans to remove it now becuase being able to manually drill stuff / tap stuff etc etc is all really useful to me.
I like the idea of putting a drive on the front...

What is an EDM machine?

[neilw20]

Spark erosion.
Electrical discharge machining - Wikipedia, the free encyclopedia

The head nod is mostly caused by the friction on the gibs, and the screw behind the column, pulling against the friction.
Move head down, and stop.
Put dial indicator under spindle.
Now slowly start to move the head up. The spindle nose goes down further before changing directions.
That amount is the head nod.
Mine is about 35 micron (0.035mm) ~~ 0.0013"
I had to use a surface grinder on the gib to get it that good. Before that was about 4 times as bad, at best.

Nice idea that green tapping buttons on the handle, but the shaft contact is so unreliable I use the forward reverse/buttons.

Deburring,countersinking:
I use the tapping buttons to make it run backwards with a drill bit, push down against job, sitting on a piece of wood, to align.
Press the button back to forward and it is perfectly aligned with hole. Crude, but very effective, as the old school did it.
I might make a short movie one day.

Where in NZ are you? I am going to NZ later in the month to work on 5 axis machine.

[mrpackethead]

Spark erosion.
Mine is about 35 micron (0.035mm) ~~ 0.0013"
I had to use a surface grinder on the gib to get it that good. Before that was about 4 times as bad, at best.

For my applicaiton, 0.035mm x 4 will still be ok thats 0.12mm I'm not going to loose any sleep about that at all. However this stuff is how we run nicely 4

Where in NZ are you? I am going to NZ later in the month to work on 5 axis machine.

I'm about 25km north of Wellington. If your about, love to say hello.. What part of Oz are you in.

[mrpackethead]

Hi, there, well, after almost six months, i've got back to working on finishing this project. Drives, ESS all wired up and, i've been able to make the motors run. It was a wee bit exciting to see the table move back and forward.

I need to do a bit of tidying up of cables etc and making everythign nice and tidy. My Mill is sitting on a really solid stand that has a shelf in it, which is really good as its a good place to stick all the electronics.


A couple of questions.

(a) What level of micro-stepping is recommended. I have 5mm pitch Ballscrews. I'm currently set up using 8000 microsteps per rev, and it seems to work ok.
(b) Any recommendations on what rates of acceleration and velocity for the XYZ motors?

(c) Whats a good way to for setting up an E-Stop on the machine itself. The Factory E-stop kills the AC to the spindle, but obvsiouly wont' kill the motors etc etc. I could probalby modify the E-Stop on the machine to kill everthing but it probably is better that its connected back to the Computer?

(d) Any recommendations for setting up X/Y/Z stop limits?

(e) Has anyone done any control of the Spindle itself? Just seems logical to control that as well.

Well, at least i can see light at the end of this tunnel!!

[mrpackethead]

Well what do you know, it works.

[handlewanker]

.........is that a drill chuck you're using as a milling chuck?.....you naughty boy.

I have to wonder at the sanity of some people.........one, I won't mention, went and bought a 13mm keyless chuck with R8 arbour for about $90.....an ER32 milling chuck with a set of collets is just a bit more than that price.....(a set means those that are needed to hold the standard shank cutters for Imperial and Metric up to 19mm diam, about 4 or 5).
Ian.

[mrpackethead]

.........is that a drill chuck you're using as a milling chuck?.....you naughty boy.

I have to wonder at the sanity of some people.........one, I won't mention, went and bought a 13mm keyless chuck with R8 arbour for about $90.....an ER32 milling chuck with a set of collets is just a bit more than that price.....(a set means those that are needed to hold the standard shank cutters for Imperial and Metric up to 19mm diam, about 4 or 5).
Ian.

I guess it is. I remember the guy from Machineryhouse who sold me the machine said it will do the job just fine.. And it "seems" to do the job. Sounds like there is a better thing to do...

I'm a *complete* newbie to this, so I'm fully expecting that there is a lot to learn. ( yesterday i learned the difference between an end mill and a slot drill )..

What difference does using a 'milling' chuck with collets use, over using a drill chuck..

Any suggestions as to what i should buy to fit my mill?



Also, for the job above, ( which is really what i bought this thing to do ) i'm cutting holes ( they are not just circles ) in a cast aluminium box for plugs/sockets etc. Its 4.5mm thick. I dont' want to go bigger than a 4mm cutter, otherwise the corners in the holes are too big of a radius.

Shoudl i use a end mill or a slot drill, and how much should i take out in each pass?

Sorry for the newbie questions..

[handlewanker]

Hi, the slot drill will drill into the material in one pass whereas the end mill having the centre in the end cannot......both can be used to mill sideways etc.

If you are holding your cutters in a drill chuck there is a chance that the sideways pressure and vibration will cause the chuck to open.

A good size milling chuck would be the ER32 (if you only have 3 Morse in the spindle) which will hold all cutters drills etc up to 19mm diam, but you only want to have a few collets for the standard cutter shank sizes, like 1/8", 1/4", 5/16", 1/2", 5/8", 3/4" for the Imperial sizes and as the collets will close down 1mm they will also hold the Metric sizes with the same set of collets........I prefer to have a collet for the exact size as it places a strain on the collet if it has to constantly be squeezed down to the next size.

You can buy an ER32 chuck and basic collet set on EBAY for around $100 that will hold all your cutters, but don't get excited and buy the full set of 2mm up to 19mm to hold drills etc as it's a pain to have to remove a collet just to get the next drill size, that's where a drill chuck comes into it's own.

I expect you've got 3 Morse in your spindle.....the fact that you are using a drill chuck means you would have 3 Morse, otherwise you'd be investing in a set of R8 collets.

With an R8 spindle and Imperial and metric collets only for the cutters( they only fit one particular size) and a drill chuck with a 3/4" parallel shank, that is all you'd want.

Any other tooling will depend on your shank type.

To answer your question, you "could" probably get away with the drill chuck if that is what you have been using, as you are drilling down through thin metal and only cutting sideways with a small cutter.

Cut half the depth with a slow feed rate......speed about 2,000 rpm for High Speed Steel cutters, double that for a carbide one, and Kerosene brushed on as a cutter lube, but don't try that lark in a drill chuck with steel and bigger cutters.

You'll find that aluminium is a sticky material and can clog the teeth of the cutter, so in that case it might be better to use a slot drill which has two flutes (some have 3) and is less prone to clogging up.
Ian.