Author Topic: Building a milling machine (Read 133764 times)

NormanV · « **on:** February 28, 2014, 01:16:16 PM »

Some of you may have noticed my questions regarding problems that I have been having setting up to cast aluminium. I have been doing this as I am planning to build a milling machine. I have based the design on the body of Dave Gingery's shaper as it allows adjustments to be made to the build to achieve the accuracy needed (I hope). Here is a sketch of what I am planning.

NormanV · « **Reply #1 on:** February 28, 2014, 01:24:49 PM »

The main body will be aluminium castings and I will recycle parts from old machines where it will achieve accuracy. For example the fine vertical feed is a lathe topslide mounted on a thick wall steel tube that also carries the motor. I have used the tube as it allows me to adjust the verticality of the head in relation to the table. Any comments would be appreciated.
Norman

NormanV · « **Reply #2 on:** February 28, 2014, 01:33:57 PM »

I may use a coordinate table for the X and Y axes in order to save time but I have made the patterns to cast my own in aluminium if I decide to. Here are some of the patterns.

NormanV · « **Reply #3 on:** February 28, 2014, 01:45:45 PM »

The first casting that I did was for mounting the lathe topslide to the steel tube across the top. I had been having problems getting my moulding sand to the right consistency and the casting turned out very rough so I had to machine it all over. Since then I have not had those problems.

NormanV · « **Reply #4 on:** February 28, 2014, 01:58:08 PM »

After machining the casting I attached the cross slide with a steel disc that I had as a mounting plate between the two.
The next casting was for the front of the machine where the angle plate shown in the diagram will mount. My first attempt warped but a second try was successful.

NormanV · « **Reply #5 on:** February 28, 2014, 02:02:05 PM »

The castings are getting more straightforward to produce as I get more practice at it. It is a couple of years since I last did any casting. Here's a collection the I have done over the last ten days or so.

mattinker · « **Reply #6 on:** February 28, 2014, 02:05:02 PM »

Casting is such fun!

NormanV · « **Reply #7 on:** February 28, 2014, 02:05:20 PM »

Yesterday I assembled the base of the body. The holes are were in the pattern to provide support for the sand over the large area of it. I will be casting the upper sections of the body over the next few days.

NormanV · « **Reply #8 on:** February 28, 2014, 02:07:15 PM »

Yes Matt it is fun. When I was doing it before I was searching around for things to cast just for the pleasure. I still have a tee handled allen key that I made simple because I could.

NormanV · « **Reply #9 on:** February 28, 2014, 02:11:26 PM »

This morning I loosely assembled the top onto the base just to see what it will look like. The extra side pieces will be in there eventually.

superc · « **Reply #10 on:** February 28, 2014, 02:11:55 PM »

Hi Norman.
I like your concept. I note that you too feel an overhang of the mill head is (or should be) allowing greater Y axis travel. That was the approach in my own speculation at http://madmodder.net/index.php/topic,9585.0.html about how parts from an X2 (or SX2) could be used to build a better milling machine. I had already mentioned to a third party how where my design suffered was in my inability to come up with a ram head type mount for the mill head that would allow swiveling or angle adjustments. Looks like you solved it and also the issue of designing a knee for yours.

My biggest concern is your decision to make the body out of aluminum. I forsee both acoustical and rigidity issues. I believe going with green sand cast iron may be a better choice, but I will shut up now. I look forward to seeing how this develops.

NormanV · « **Reply #11 on:** February 28, 2014, 02:19:02 PM »

Yes Superc I read your post about your milling machine. The tube that I have used is long enough for me to adjust the overhang but it is not my intention to have it as an adjustment to use in the operation of the machine. I intend to set it the once and lock it in position when it is set in the best position.
As for rigidity I am making the aluminium quite thick, typically 18mm and I will fill all the voids with concrete or an epoxy based filler when it is complete. I hope that that will be sufficient.
Norman

NormanV · « **Reply #12 on:** February 28, 2014, 02:25:22 PM »

I was particularly pleased with how the casting for the hold down caps on the tube turned out. It is the most complicated pattern so far and I was concerned over how easily it would release from the sand but I had allowed plenty of draught and it released easily. I used the steel tube as a former for the curved section to save having to machine it. I smoked it with a candle and it released easily.

superc · « **Reply #13 on:** February 28, 2014, 03:54:23 PM »

Sir, regardless of intended use today, I salute you for coming up with a doable design that does indeed allow both Y axis adjustment and also angling of the head if so desired. You may wish to think about putting a key way into the clamp and a key into the pipe so as to prevent any tendency for the head to cause the pipe to pivot (i.e., angle).

rick barnes · « **Reply #14 on:** February 28, 2014, 06:13:59 PM »

I really like that idea. Is there any problems with moving the Z axis from below the table as far as rigidity is concerned?

NormanV · « **Reply #15 on:** March 01, 2014, 02:24:47 AM »

The idea is to use the under table adjustment to set the table height approximately and then lock it in position. The top Z axis slide will then be used for fine adjustment.

rick barnes · « **Reply #16 on:** March 01, 2014, 02:48:17 AM »

Well, definitely a thread to watch. I've been trying to build one for years.

chipenter · « **Reply #17 on:** March 01, 2014, 03:05:36 AM »

Have you looked at the Dore Westbury machine http://www.lathes.co.uk/dore%20westbury/index.html of a similar design with a epicyclylcic pully for slow speeds ?

NormanV · « **Reply #18 on:** March 01, 2014, 04:06:19 AM »

I am familiar with the Dore-Westbury machine. A good friend of mine built one many years ago but without the gearbox. I shall be using a two step pulley combined with a variable speed drive to achieve speeds of 2300-100 RPM

shipto · « **Reply #19 on:** March 01, 2014, 06:00:42 AM »

I too would like to build one I just dont have a mill to make it

NormanV · « **Reply #20 on:** March 01, 2014, 07:46:23 AM »

Nor do I just a lathe and a drill.

NormanV · « **Reply #21 on:** March 02, 2014, 08:17:05 AM »

How frustrating! The weather has been good for the last week and I have been able to make castings every day. Today it is wet and windy and I am getting impatient. The forecast for tomorrow isn't too good either, it looks as if I will have to wait till Tuesday to get started again. It's probably not a bad thing though, my sand was getting a bit dry and I had a couple of moulds drop out as I turned them. I damped the sand down yesterday and the delay is allowing it to settle down again.
I have spent some time this morning making patterns for the pulleys. I am planning to use multi-groove belts as one of the pulleys is going to be quite a small diameter and a vee belt would struggle to get around it.

awemawson · « **Reply #22 on:** March 02, 2014, 08:41:27 AM »

Norman,

My routine used to be, knock out the sand from the moulding box onto a swept floor, water with a watering can, cover with pvc sheet and leave over night, then give it a good turning over with a shovel the next morning adding more water if needed, then return it to the storage container (where it was reasonably sealed) via a suitable sieve ready for next time. When I get set up again I'll make a muller.

I've been known to have it turning in a cement mixer with a large gas flame impinging when I've over done the water

Arbalist · « **Reply #23 on:** March 02, 2014, 09:47:16 AM »

Looking good Norman!

NormanV · « **Reply #24 on:** March 02, 2014, 10:40:09 AM »

Thank you Arbalist.
Andrew, I need to do that. I have been putting the sand back into its storage box without tempering it and it has gradually got drier. I'm trying to be tidy!

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Author Topic: Building a milling machine (Read 133764 times)