Some progress towards a new mill. What about CNC?

[John Hill]

The painters are nearly finished in our new house and the workshop looked very spacious and cosy when we went to see it last week.  One of the intentions in the new shop is to have mill and after looking around the Sieg SX4 looks interesting.

At last, after me messing around with local 'distributors' Sieg have agreed to ship me one from China, almost to the doorstep, well the port is only 60 miles away...  price direct is very good too!

Now this is what one of these looks like:-



Owner's review here http://www.mini-lathe.com/Mini_mill/Reviews/SX4/sx4-rvw.htm

I guess that is a fairly standard configuration for a dovetail column mill and maybe nothing really remarkable about it,  though I wouldnt know as I know less about mills than I did about lathes when I bought mine a couple of years ago and that turned out OK.

The question though, what about a potential for CNC?  Would this machine be a good or bad choice for maybe, just maybe, dabbling in CNC in the future?

I have not placed the order yet.

John

[spuddevans]

Wow!!! (wipes drool off the keyboard before it shorts out) That's a nice mill, and a decent working size too.

The question though, what about a potential for CNC?  Would this machine be a good or bad choice for maybe, just maybe, dabbling in CNC in the future?

I would think that it will convert as easily as the lower models, and you can easily attach steppers to the acme leadscrews if you want to try cnc without heavily modding the machine or buying ballscrews.



But on second thoughts, I really think you would be really unhappy with this mill, you should just get it delivered to me and I will send you my (almost) converted X2


Tim

[John Hill]

But on second thoughts, I really think you would be really unhappy with this mill, you should just get it delivered to me and I will send you my (almost) converted X2


Tim

You could well be right Tim but I really should give it a bit of a trial first.  If its no good you can come and take it home as carry on baggage!

[sbwhart]

Wow I do like the look of that,  I've got a SX3 and I'm very pleased with it, as for CNC well they CNC the SX2 and SX3 so that Baby should convert as well.

Stew

[John Hill]

I have gone cool on the Sieg SX4 which I would have to order direct from China,  OK, cheaper and I am sure it is a nice machine but I am just too conservative to buy something I have not been able to look at first.

So I got a bit carried away thinking about turret mills and found this one:

Luxcut mill by aardvark_akubra, on Flickr

http://www.scottmachinery.co.nz/conventional.php?s=110&ss=140&scode=MTUR-0-0001

The dealer is not big on discounts but he does seem to steer away from the worst end of the Chinese market,  this is what he suggested when I said I knew nothing about mills but wanted something of a scale somewhat equivalent to that of the 12x36 lathe.


Of course adding vice, rotary table, dividing head with tail stock, MT3 adapter for the M8 spindle and a few cutting tools pushes the price up a bit.

I am still wavering a little but I think there is still room in the new shop!

Any opinions gratefuly accepted!

[John Hill]

Further on the potential new mill.  This mill has an up and down table (I think that called a 'knee'?) now the question is, I presume the knee would be raised when taking sucessive cuts rather than lowering the quill?


When would one use the quill, except for drilling and/or tapping?

[kwackers]

Further on the potential new mill.  This mill has an up and down table (I think that called a 'knee'?) now the question is, I presume the knee would be raised when taking sucessive cuts rather than lowering the quill?


When would one use the quill, except for drilling and/or tapping?

That's about it...

Nice to have the option though, sometimes what I'm doing suits being able to drop the quill rather than raise the knee. Just don't drop it too far as you lose rigidity and make sure you lock it for the same reason.

[Bogstandard]

John,

That is basically the same one I have, here it is called an 836.

http://www.chesteruk.net/store/836_turret_mill.htm

About 2/3rds the size of a standard Bridgey (I couldn't get any larger in my shop), it complements our lathe perfectly. Plus I can reach all controls whilst sitting down to work, that was a major concern for me.

I only ever use the quill for drilling, purely for rigidities sake. I always use the knee for boring and putting on the cuts. But I do have power feeds on all axis, and that makes the machine an absolute joy to use, and so does the variable speed. Just dial in until you get a happy sound out of the cutter.
I also fitted the third axis DRO to the knee, and a cheapo scale to the quill. The two axis display that was taken off was then used as the 3rd & 4th axis display on my lathe, so I recovered some of my costs.

There are a few things that are missing off it compared to a full sized bridgey, that is the power downfeed for the quill (which from reading other peoples reports, it is no use anyway) and also it doesn't have the 'nod' on the head, which to me, is looking for trouble if you used it,  as it is just another thing to go out of tram. Also there is no fitting to the back of the head ram, so you can't fit say a slotting head. I can't swing mine around anyway, so I have never missed it.

Mine has performed faultlessly in over two years that I have had it installed, except for a bearing change that cost just over 2 squid and took ten minutes to change, and I also damaged the R8 spigot that stops things rotating in the spindle, that was just a matter of fitting a new dog nosed grub screw and only took minutes.

So all in all, I am very happy with it.


John

[kvom]

The only functional difference I see vs. a Bridgeport is the quill downfeed and provision for a quill stop.

I use mine to set the depth for blind holes and counterbores.  The process is to touch off the tool to the work surface, install the quill stop, raise the spindle, and then raise the table by the desired depth.  The stop then tells you when you've reached the desired depth.

Since there's no power downfeed, I assume that for boring you could use the fine feed wheel.  I've never used mine on the BP, but perhaps Bogs can comment on ease-of-use vs. the knee.

I have power feed on the X-axis, and wouldn't want to be without it.  I use an electric drill with a shop-made adapter for raising and lowering the knee.

Since my BP has a 3PH motor, I power it via a VFD.  This is very convenient for speed control, and I rarely need to change the belts. 

[John Hill]

Further on the potential new mill.  This mill has an up and down table (I think that called a 'knee'?) now the question is, I presume the knee would be raised when taking sucessive cuts rather than lowering the quill?


When would one use the quill, except for drilling and/or tapping?

That's about it...

Nice to have the option though, sometimes what I'm doing suits being able to drop the quill rather than raise the knee. Just don't drop it too far as you lose rigidity and make sure you lock it for the same reason.

Thanks

[John Hill]

Further on the potential new mill.  This mill has an up and down table (I think that called a 'knee'?) now the question is, I presume the knee would be raised when taking sucessive cuts rather than lowering the quill?


When would one use the quill, except for drilling and/or tapping?

That's about it...

Nice to have the option though, sometimes what I'm doing suits being able to drop the quill rather than raise the knee. Just don't drop it too far as you lose rigidity and make sure you lock it for the same reason.

Thanks.

[John Hill]

Hi John,  Typically on this style of mill the quill is used for the Z-Axis movements on milling and drilling operations.  The knee is used on positioning and set up operations.  There are a lot of reasons why one would like to have extra travel in 'Z'.   I've got a bridgeport knee mill and I often find myself wishing I had about 2-more inches of travel in Z.  I've seriously considered getting one of those 4-in spacer blocks to put at the top of the column.

In my mind there are two reasons for large knee travels, I'm sure others will add more...  The two biggest are different sizes of material.  Sometimes you need to work on a large flat piece of plate stock.  You'll need to crank the knee way up to get that flat plate into the area where it can be reached by the head of the mill.   Then say your next piece to cut is in the side of an injection mold or into the end of a large engine cylider.  You'll need to crank the knee down to reach the lager stock.

The second reason for the lage knee travel relates to tool offsets.   Imagine you are grabbing a tiny little cutter (1/4-in or smaller) directly in a collet.  It is only going to stick out of the end of the quill a tiny bit.  You'll need to bring the work piece up close.   Then imagine you are going to use a boaring bar on a large engine cylinder, or big reamer, say 3/4-in) You'll need to put that long reamer in a big drill chuck which is itself going to hang down from the quill several inches plus the length of the reamer.  The tip of that boring bar might start out 5-in below the tip of the 1/4-in cutter and the tip of the reamer may START 8~10in below the tip of that cutter.  You will then need to move the knee.

A lot of it depends on what you are going to make.  For the work that I do, I find that I use the knee motion a lot between various parts.  If one is only ever going to work on very small pieces then it isn't needed.  Reamers can be cut shorter and there are lots of ways around things up to a point.  If you ever need to add water liens to an injection mold or some such you'll be glad you have it.

Thanks Kenneth, I have a whole book of potential projects in my head!  Electric bicycle/tricycle, tilting three-wheeler motor car/cycle, all manner of small engine projects plus of course a variety of shop made tools!

I do not think I will be boring any big cylinder blocks but really nothing is out of scope.  Except very small models like the beautiful work I see some others producing!

One project I had in mind was a model traction engine, 4" or bigger, as traction engines are 'big' in this town but after checking the prices of kits I sort of cooled off on that aspiration!  The kit for one I would like, mind you it is fully machined and only really needs fettling, painting and assembly, would buy about 4 new cars!  (the sort of cars us retirees might buy anyway).

[John Hill]

John,

That is basically the same one I have, here it is called an 836.

http://www.chesteruk.net/store/836_turret_mill.htm

About 2/3rds the size of a standard Bridgey (I couldn't get any larger in my shop), it complements our lathe perfectly. Plus I can reach all controls whilst sitting down to work, that was a major concern for me.

I only ever use the quill for drilling, purely for rigidities sake. I always use the knee for boring and putting on the cuts. But I do have power feeds on all axis, and that makes the machine an absolute joy to use, and so does the variable speed. Just dial in until you get a happy sound out of the cutter.
I also fitted the third axis DRO to the knee, and a cheapo scale to the quill. The two axis display that was taken off was then used as the 3rd & 4th axis display on my lathe, so I recovered some of my costs.

There are a few things that are missing off it compared to a full sized bridgey, that is the power downfeed for the quill (which from reading other peoples reports, it is no use anyway) and also it doesn't have the 'nod' on the head, which to me, is looking for trouble if you used it,  as it is just another thing to go out of tram. Also there is no fitting to the back of the head ram, so you can't fit say a slotting head. I can't swing mine around anyway, so I have never missed it.

Mine has performed faultlessly in over two years that I have had it installed, except for a bearing change that cost just over 2 squid and took ten minutes to change, and I also damaged the R8 spigot that stops things rotating in the spindle, that was just a matter of fitting a new dog nosed grub screw and only took minutes.

So all in all, I am very happy with it.


John

Thanks John,  it sure looked big enough in my eyes although it was rather dwarfed by the more serious machines that dealer offers,  it was very interesting to walk around their show room and I admit I did pause and dream for a moment beside the big shaper in the used equipment section!  Very nice people working their too with absolutely no condescension towards the old guy who did not have much of a clue asking the questions!

Power feeds are an option of course and I can always add those later but so far, touch wood, the muscles are still up to the job and anyway, maybe a power feed at least for the X-axis would be a good project for those geared motors I have carried down form Wellington.

The DRO display has three channels, I will be up in Christchurch for a hospital appointment next week and will discuss a knee DRO with them.

The quill has a stop and vernier scales for both quil movement and stop position.

You know John, I would not have ever thought of spinning the head around to mount anything if you had not mentioned it!  I guess it is vertical slots only that would require a slotting attachment?

 

[John Hill]

The only functional difference I see vs. a Bridgeport is the quill downfeed and provision for a quill stop.

I use mine to set the depth for blind holes and counterbores.  The process is to touch off the tool to the work surface, install the quill stop, raise the spindle, and then raise the table by the desired depth.  The stop then tells you when you've reached the desired depth.

Since there's no power downfeed, I assume that for boring you could use the fine feed wheel.  I've never used mine on the BP, but perhaps Bogs can comment on ease-of-use vs. the knee.

I have power feed on the X-axis, and wouldn't want to be without it.  I use an electric drill with a shop-made adapter for raising and lowering the knee.

Since my BP has a 3PH motor, I power it via a VFD.  This is very convenient for speed control, and I rarely need to change the belts. 

Hi Kvom,  it does have a quill stop with a vernier setting but you are right there is no power downfeed though if I can make a power downfeed for my shaper I guess I should be able to fashion something for the mill.  My workshop is for recreational purposes so spending time on making bits for the shop is a valid activity!

VFDs seem grossly overpriced in this country and although used 3 phase motors are scrap value new ones are expensive too.

[Bryan]

VFDs seem grossly overpriced in this country and although used 3 phase motors are scrap value new ones are expensive too.

A 2HP is about $150 AUS with shipping from Honkers: http://cgi.ebay.com.au/VARIABLE-FREQUENCY-DRIVE-INVERTER-VFD-NEW-2HP-1-5KW-3-/180577957540?pt=BI_Electrical_Equipment_Tools&hash=item2a0b48f6a4.

[John Hill]

Thanks Bryan, that is a lot less than I was finding 18 months ago.

[Bryan]

In another 18 months they'll be free!

[Jonny]

Certainly the X axis power feed can be done at a later stage and so could the 3rd scale better mounted off the quill so all 3 readouts on same box.
Maybe just use a simple scale for knee.

I am tempted by these machines but take up floor space. I never had a look how the spindle speeds are changed, how easy and how slow to do. If it a spanner job to change speeds i would be very tempted over anything to go vari speed to use straight away.

[Majorstrain]

VFDs seem grossly overpriced in this country and although used 3 phase motors are scrap value new ones are expensive too.

A 2HP is about $150 AUS with shipping from Honkers: http://cgi.ebay.com.au/VARIABLE-FREQUENCY-DRIVE-INVERTER-VFD-NEW-2HP-1-5KW-3-/180577957540?pt=BI_Electrical_Equipment_Tools&hash=item2a0b48f6a4.

I have one of the 2.2kW 230V versions.
It works very well with manual control both from the front panel and remote buttons and potentiometer. It has a robust drive circuit and the output short circuit protection works well. (don't ask how I know that  )

But be warned though, most units I have heard of are missing the RS485 chip and/or some components of the braking resistor circuit. It's an easy problem to fix if you can solder or know a mate that can. The parts are cheep on eBay.
This is not a reason to avoid buying one especially for the prices they are selling at. Just a hassle if you plan to computer control the VFD or use an external braking resistor.
More info can be found on the Mach3 forum. http://www.machsupport.com/forum/index.php/topic,14182.msg119339.html#msg119339  Well worth the read and I have put a circuit diagram of the drive board in a post lower down. (reply 189)

Cheers.
Phil