Ram-type milling machine

[lukahr]

I started to work a little on my enclosure for the machine. To get overall idea how it will look like and where I need to prepare mounting points on casting.
Electrical cabinets will be under tool changer, on left or right side of the machine under table it will be reservoir for flood coolant.
I want to fully enclose whole machine. I'm still deciding if I should build enclosure from steel tubing or alu extrusions.

For now it looks something like this.
Should I make enclosure free standing or connected to machine base ?

[lukahr]

There has been some progress in design.
I have been working on tool changer for some time and also couple of days on metal sheet work
Now the machine really getting its final shape.
There is still lot to do with CAD design but slowly getting there

I also started to ordering steel inserts for molds.

[peteeng]

Hi Luka - Looking like a bought one Peter

[lukahr]

Hi Luka - Looking like a bought one Peter

Thanks, i'm trying to make it look as professional as i can

I have been thinking about my worktable design and i dont know if my solution is best.

In design now I have casted (UHPC 100mm) worktable with 30mm steel plate (probably c45 or cast iron) on top for t-slots . (total thickness 130mm)
I would assemble machine together allign columns and bridge to linear rails and mount table to them.
After that i would mill top surface and t slots when machine will be fully assembled.

Is that good ?

Or should i mill t slots and face mill whole table before assembly on different machine and align top bridge according to table surface ?

Also is worth to make two part table UHPC + steel plate on top or should i just go with 50mm thick steel C45 or something similar.

Any thoughts from you guys ?

[peteeng]

Hi Luka -
1) can the machine reach the entire table perimeter? Usually they can't the table is bigger then the XY travel
2) If you can make parts prior to assemble to correct spec then this is the better production route. Then assembly issues are separate from component issues
3) Two part table Hmmm as long as the UHPC has the same coefficient of expansion as the steel then your good. If they are different then as temp changes the table will warp. Just like a bimetallic strip... Peter

eg steel is about 12um/m
HE80AG which I use is 13.7um/m

but "cement all" CSA is 2.53 so this would be a mismatch

[lukahr]

Hi Luka-
1) can the machine reach the entire table perimeter? Usually they can't the table is bigger then the XY travel
2) If you can make parts prior to assemble to correct spec then this is the better production route. Then assembly issues are separate from component issues
3) Two part table Hmmm as long as the UHPC has the same coefficient of expansion as the steel then your good. If they are different then as temp changes the table will warp. Just like a bimetallic strip... Peter

1. Yes my design is made like that, i can mill whole working table 1100x700mm.

2. Yes that is correct but getting someone to mill me a table of that size to 0.01mm will be a challenge or it will cost too much.
My idea was to only mill bottom part of table for linear carriages mounting points and later mill top side myself.
That way table will be perfectly parallel to bridge. But if bridge is not perfectly straight and square than my table wont be also.
But my goal is to make bridge perfectly straight in fist place and align it to bottom linear rails as good as i can.

3. NANODUR UHPC has Thermal expansion ?T 12.0 · 10-6 [1/K], that is pretty much the same as steel.
(Durcrete uses S355J2 steel for inserts and they are saying thermal expansion is pretty much the same)

[peteeng]

Hi Luka- sounds like the bases are covered. Mill it yourself. If you set it all up and can't align machine to satisfactory level then you will have to pull it down and outsource the facing. This raises another question: how are you going to align the machine? I have been researching laser geometric alignment and laser scanning for alignment and these start at about $25000USD, well outside my budget!! I'm going to have large squares/fixtures machined local...Peter

[lukahr]

Hi Luka- sounds like the bases are covered. Mill it yourself. If you set it all up and can't align machine to satisfactory level then you will have to pull it down and outsource the facing. This raises another question: how are you going to align the machine? I have been researching laser geometric alignment and laser scanning for alignment and these start at about $25000USD, well outside my budget!! I'm going to have large squares/fixtures machined local...Peter

Yes anything with fancy laser alignment is out of question because of cost.

My plan is:
- mill all mounting surfaces for linear rails and ballscrews with side support datum's on large precision mills or bohrwerks - outsourced (i will have to trust them that milled surfaces are parallel and straight)
- Glue together all parts that does not require high precision +-1mm
- then i will use large precision granite squares and granite plates to make everything right and square. (columns+bridge)
- I will adjust bridge squareness with levelling bolts according to base linear rails that has been machined and inject epoxy to fix in positions
- Spindle will be trammed with shims
- Lastly milling table will be surfaced by my machine

Big part of my precision will be outsourced milling made to steel inserts in my castings, so if that will be good than i do not worry about machine precision and aligning

[lukahr]

And today I also found course aggregate that I have been looking for quite some time.
Found it in local store that I forgot to check .

Exactly right type of material and right granulation
Balsatsplit in 2-5mm granulation.
I went to pick up 500kg and tomorrow I'll go for additional 500kg

After that I only need fine 0-2mm quartz sand and PCE superplasticizer.