Buying a CNC Lathe & CNC Mill - Need Advice

[mechanica]

If you are really concerned about the $8000, just buy the base machine for $5000 and build / find a stand. If you go the Taig route you need to make up a stand anyway. When I purchased my 770M I opted for the Tormach stand - it was really well engineered and I couldn't make it for what they charge by the time you include paint etc.

The Tormach is very easy to fix if you have some mechanical / electronics aptitude. Tormachs are not industrial machines so you should be a prepared somewhat for the eventual failure. But the good news is Tormach offers full schematics, and you can order all the parts directly from Tormach for fairly reasonable prices. For example, if your spindle goes bad you can order a new cartridge. Other than a stepper driver burning out I've had no major failures on the Tormachs I have used over the years. (I have them in my shop, and I worked with them in the past).

One of Tormach's big benefits is Path Pilot. Yes it's Linux CNC under the hood, but they have added a number of very handy conversational programming functions that work well.

Thanks for the info.
The 440 looks like a (pretty smart) attempt to capture the high end hobbyist machine market.

Truthfully, I had hoped to get acquainted with CNC milling on something in the $4K range (tooling and all).
To jump from nothing to an 8K machine for the home is quite a jump.

With the opposition on the forum to me purchasing a CNC with my limited knowledge, I'm opting now to put off the purchase decision till (god knows what).
In the mean time, I'm going to refocus my efforts on learning Fusion 360, perhaps learning some G-code and then circle back on a Mill decision.
I'll be sure to keep the 440 in mind when making a decision - especially with almost unanimous approval of it here.


Thank you all for your help!

[RB211]

Thanks for the info.
The 440 looks like a (pretty smart) attempt to capture the high end hobbyist machine market.

Truthfully, I had hoped to get acquainted with CNC milling on something in the $4K range (tooling and all).
To jump from nothing to an 8K machine for the home is quite a jump.

With the opposition on the forum to me purchasing a CNC with my limited knowledge, I'm opting now to put off the purchase decision till (god knows what).
In the mean time, I'm going to refocus my efforts on learning Fusion 360, perhaps learning some G-code and then circle back on a Mill decision.
I'll be sure to keep the 440 in mind when making a decision - especially with almost unanimous approval of it here.


Thank you all for your help!

I had the same reasoning you did, to learn CNC. Upon first real use, the limitations were instantly noticed, especially after watching everyone else on YouTube with their basic CNC's that at least had the quick change Z height settable tooling. What the Taig in stock form actually gives you is a mill with a spindle that works like a cheap router. Anything with an R8 or ISO spindle is instantly 100 times better for CNC.
Also, I bought my Taig as "CNC Ready" and used my own steppers and a Centroid Acorn. My Taig ready to go will be closer to 6k, not 4k, and I still need to buy more tool holders, still buy a variable speed spindle motor and driver. I could easily spend another 1,000$.

Do your research, look at used machines, look at doing a CNC controller retrofit. Look at a used Tormach 440. I can honestly tell you that chasing down that last .001 positioning error is NO FUN if you go DIY.

[pinstripe]

As you can see, I am still not done paying money to get my Taig working to my satisfaction, why I am suggesting to you that you just buy a Tormach. I wish someone told me what I am telling you.

I smell an opportunity here. Someone wants an upgraded Taig, and someone with an upgraded Taig wants a Tormach

mechanica. How complicated are the parts? What are the tolerances? How many identical parts do yo need to make? You might be surprised at what can be made manually in low volumes. Chris from Clickspring made this work of art using low-cost machines and plenty of skill. Your budget is not going to get you far in the ready-to-run CNC world unless you find a used, well tooled machine. Ongoing costs are going to be higher with a CNC as well.

[RB211]

I smell an opportunity here. Someone wants an upgraded Taig, and someone with an upgraded Taig wants a Tormach

I wouldn't screw him over like that, to charge what I have in it, for the end result. I am too deep into it to abort the launch.

[skunkworks]

Yes - it is nice having tooling that you can set and forget. There are things you can do to get around it.

Before we had the some of our other machines we had a simple router with a roto-zip for the spindle. We just setup a simple tool length sensor (it was literally a micro-switch). This was making circuit boards - so z height was very important. (and more than 3 tools usually)

It would go like this.
Put the first tool in. Set it to the material.
when the gcode would run - it would check the first tool with the tool length sensor to get a reference.
Each tool after that would touch the tool length sensor and adjust compared to the first tool.

easy peasy

So you only have to touch off the first tool.

[RB211]

Yes - it is nice having tooling that you can set and forget. There are things you can do to get around it.

Before we had the some of our other machines we had a simple router with a roto-zip for the spindle. We just setup a simple tool length sensor (it was literally a micro-switch). This was making circuit boards - so z height was very important. (and more than 3 tools usually)

It would go like this.
Put the first tool in. Set it to the material.
when the gcode would run - it would check the first tool with the tool length sensor to get a reference.
Each tool after that would touch the tool length sensor and adjust compared to the first tool.

easy peasy

So you only have to touch off the first tool.

Yes, on the router, but when you machine away the original touch off surface, things get more complicated.

[skunkworks]

? I don't understand what you mean.

Yes, on the router, but when you machine away the original touch off surface, things get more complicated.

[reggie_obe]

? I don't understand what you mean.

Difference in length between tool #1 and #2 is a value stored and used for compensation of position?

[RB211]

? I don't understand what you mean.

Your Z height for say a circuit board doesn't change. Like most projects on a router. My mill is setup to place a tool touch off probe on top of the workpiece each time I change tools. Well, what happens after the first op? Faced off the top of my surface I would place the tool touch off probe. Not having a tool library and needing to touch off the Z every time I change a tool is cumbersome at best.
Routing a circuit board you don't have that issue.

[Knires]

Thanks for the info.
The 440 looks like a (pretty smart) attempt to capture the high end hobbyist machine market.

Truthfully, I had hoped to get acquainted with CNC milling on something in the $4K range (tooling and all).
To jump from nothing to an 8K machine for the home is quite a jump.

With the opposition on the forum to me purchasing a CNC with my limited knowledge, I'm opting now to put off the purchase decision till (god knows what).
In the mean time, I'm going to refocus my efforts on learning Fusion 360, perhaps learning some G-code and then circle back on a Mill decision.
I'll be sure to keep the 440 in mind when making a decision - especially with almost unanimous approval of it here.


Thank you all for your help!

I think you are on the correct path of gaining knowledge. I would wait and look for a used 440. A few have gone in the $4k range. While waiting, try out Fusion360 or other CAD and CAM.

If you want to check out the Tormach software on the control side, you can go here: https://hub.pathpilot.com/ That should get you able to CAD -> CAM -> Simulate machine a part to see what the workflow is like. Less broken bits that way as well!

[skunkworks]

Maybe I am not getting my point across..

You only touch off the first tool to the stock. The tool then gets measured by the tool length switch. After that - each tool touches the tool length switch and the tool offset is calculated based on the first tool. (so the length is correct to the part)

sam

Your Z height for say a circuit board doesn't change. Like most projects on a router. My mill is setup to place a tool touch off probe on top of the workpiece each time I change tools. Well, what happens after the first op? Faced off the top of my surface I would place the tool touch off probe. Not having a tool library and needing to touch off the Z every time I change a tool is cumbersome at best.
Routing a circuit board you don't have that issue.

[Bented]

Difference in length between tool #1 and #2 is a value stored and used for compensation of position?

Tool Offsets, some controls offset the difference in size between tool #1 and all other tools in the library.
Work Shift moves the Zero position of tool #1 therefore all other tools as well.

A perfect example is the length of a part held in a lathe spindle, you can move the Z Axis 0.000 the usable length of the lathe using the #1 tool and all other following tools used have the same zero position.

Do not confuse tool offsets and work shift.

[Dragons_fire]

I didnt see anywhere that anyone has mentioned it, but at least half your budget should be for tooling. Youre going to need tool holders (eg, R8), clamps, drills, endmills, chip collection, measuring tools.... the list is almost endless.

[RB211]

Maybe I am not getting my point across..

You only touch off the first tool to the stock. The tool then gets measured by the tool length switch. After that - each tool touches the tool length switch and the tool offset is calculated based on the first tool. (so the length is correct to the part)

sam

And the tool touch off probe is sitting on the same plane as the bottom of the part? What if your part is in a vice, and the touch off is on the bed of the mill? How do you account for that?

[Sparky_NY]

And the tool touch off probe is sitting on the same plane as the bottom of the part? What if your part is in a vice, and the touch off is on the bed of the mill? How do you account for that?

Does not matter where to tool probe sets so long as it remains in the same spot for the job ( or its location is repeatable). What you are setting is the tool offset, the DIFFERENCE in length between the various tools, the part and its location has nothing to do with that difference. Your confusion lies with the difference in tool length offset and part zero.

Its not uncommon for the operator to set all his tool length offsets before the stock is even put in place. When the stock is mounted, then all that is required is to set part zero with ANY tool and ALL tools will be calibrated due to their DIFFERENCES in length previously being stored earlier.

Another example: Lets assume you have 10 tools, all entered in the tool table along with their offsets. You do job#1 and touch off for part zero and run. Job#2 comes along, it is NOT necessary to touch each tool, you only part zero touch off with ANY of the tools in the tool table and all tools are not in calibration. The tool length offsets in the tool table never change so long as the same tools remain in each holder (tool number), what does change job to job is the part zero.

All of the above is in reference to the Z height only. X and Y are handled in almost the same manner though via the tool diameter in the tool table for each tool.

Worth noting also, that some operators set all their tool length offsets using a special fixture OFF the machine on the bench. The values obtained from that fixture are then entered into the tool table. When it is time to run a part, the part offset Z is set ON the machine with the stock in place using ANY of the tools in the table.

Bottom line, tool length offset is a OFFSET, the difference in length of the various tools measured from "some" constant Z reference. That reference can be anything, a fixture, the mill table, the part, does not matter, we are just looking for the DIFFERENCE in length between the various tools. PART ZERO is only done once and gives the control the location of the STOCK , the control then does some simple math each time a tool is changed to maintain zero at the same place on the part for every tool.

Kinda like your altimeter, you only need set it once (part zero) then it is calibrated at every altitude (different Z heights) because the DIFFERENCE in pressures vs altitudes has been previously saved (permanently) in the inner workings of the altimeter (tool length offsets in tool table). Theory is pretty much the same.

Not having repeatable length tooling is probably the reason for your confusion, you need to touch off every tool every time. Tool length offsets require repeatable Z capability. You have not been able to use tool length offsets thus far. Rather than using offsets, you just reset part zero every time you change a tool.