[lgcnc]

Hello everybody this is my first post but I have been watching the new builds on here for a while now and any input the community can give me on this build would be much appreciated.

I plan to make a 5 axis machine with the 4th axis on the milling head and a rotary on the X table. Material I plan to be working with is everything form wood/aluminum to steel.
All parts will be machined from steel except the motor brackets.

Parts list
NSK C5 ballscrew 32mm diameter with 10mm lead, zero backlash
X Axis is 300mm travel
Y Axis is 1000mm
Z Axis is 200mm
These are already purchased.

Motors
The motors I plan to get are 3 steppers from Orientalmotor for the XYZ Axis and smaller ones for the other 2 rotary axises. I will also be getting encoders for them.

Controller
DSPMC

I plan on using 2 harmonic drive gears for the rotary axises
CSF-17-100-2UH gear heads or the equivalent component set with custom spindles.

Rails
30mm Hiwin linear rails I am getting these from a surplus store.

Spindle
I will be getting a KL-2200 to start and will be building my own bt30 atc motor spindle or a bt 30 tomach spindle with my own motor and atc system.

I do have some questions
1. Would a C32 breakout board with a smoothstepper work as well as the one I have listed there?
2. Are those good stepper/driver combos or should I go with something else?
3. Are the harmonic drive gear heads good enough to handle milling forces or should I use only the component set and my own built spindle?


Some notes on the images, first I have not finished the X axis design I only have a place holder table in place at the moment and there will be 4 rails supporting the table. I should have this done in the next couple of days. The frame is 6"x6'x.5" steel tube and I plan to fill them with sand to add mass. The red bottom is a steel plate bolted to the top of a row of that same tubing.

[Bl@ckrat]

200mm on z seems very short for 5 axis

I think you need to mount your spindle in the tube to reduce overhang... It seems real excessive , can't see it milling steel... And not with a router spindle either

Also you need diagonals in your gantry tube to stiffin it up , end caps is a good start

[pippin88]

I don't see an actual machine base, you need a solid base.
You table size is tiny compared to the travel along the beam.

Agreed you need to look at that massive overhang.

[lgcnc]

@ Bl@ckrat
Thanks for your reply.

Could you explain why 200mm Z is to short. Most of the parts that I have plan to make have a height no more then 150mm. I can make the Z longer easy enough, the ball screws I bought are all 1000mm travel I was going to have 2 of them cut down to make the Y and Z. I was trying to limit the Z as much as possible so as to be more rigid. I really don't want to go more then 300mm on the Z though.

Yes I noticed that the overhang was large but was hoping it wouldn't be to large but I guess not . I was trying to design it so that I wouldn't have to make a trunnion table. Would there be any way to still have the spindle rotate but with less overhang? I am not completely against making a trunnion table I was just hoping to be able to use shorter length tooling. Also if I don't have rotation on the spindle I will probably go strait for the Tormach spindle but still try to build my own.

As for the KL-2200 spindle I have no intention of using it to mill any steel. I fully plan to upgrade the spindle to one I build or the Tormach one, sorry I should have been more specific there.

Sorry I thought it was implied well enough that there would be end caps on the tubes for the bridge when I said I would be filling them with sand or if you have a better suggestion as to what to fill them with please let me know. I could but another tube on the bridge to make it 4 tubes in a square (I have enough extra of that tube to do this) if you think that would be good or I could just put diagonal supports along the back. I had actually modeled the end caps for the Z as well as ribbed supports on the inside, didn't notice that I had them turned off when I took the screenshots oops.

@pippin88
Please read the last paragraph of the original post. Sorry for being snippy but I did address everything that you said but the overhang in my original post. Probably could have worded the info about the base better though now that I look at it again.

Edit.
The reason I haven't designed the X axis yet is that I am still looking for a suitable piece of steel to make it from, when I have that I will post the design. I should have this by tomorrow.

[lgcnc]

Does anyone have on opinion on the questions I asked in the original post particularly the first two as it looks like I will have to go with a trunnion table to get 5 axis and would then be making my own spindle to go with the harmonic drive component sets?

Also are 320 oz/in motors big enough?

[pippin88]

200mm is short because of tooling.
Then you have a vice our other clamping mechanism on the table, probably 75mm high.
Very quickly you run out of Z.

For example a 12mm drill might stick out 100mm. Depending on what you are holding it in, the holder will also contribute to stick out.
You need enough Z to get over the top of your highest work piece in work holding with your longest tool.

I don't see a rotary axis modeled on the head. A rotary axis will further increase your overhang.
Overhang is necessary to some extent. The throat (spindle center to column on a standard mill) determines the Y travel. If the spindle is further out you can have more Y travel but you run into rigidity and lever problems.

[lgcnc]

I was planing to have 100mm clearance from the bottom of the tool holder to the table when the Z axis is all the way down (hard to show this without the X table finished and without exaggerating everything) but from what you are saying I should probably have about 150mm to 200mm clearance. I will work this in when I get the table modeled.

The rotary axis for the spindle is currently inside the boxed in part on the Z attached to the back plate, this is why the spindle is on the outside causing the overhang. I didn't want nor do I really need more than 200mm travel on the Z axis and I would rather have reduced levering issues and increase the rigidness as much as I can. Though it looks like I will be going with a trunnion table so I wont need space for the rotary on the Z unless someone suggests a good system to have a rotary on the spindle.