Aluminum vs steel blocks for scale install

[rronald]

I've got all the parts for a Touch DRO install on my PM 1130-V lathe either here or on the way. Was thinking about the installation. I've been planning to make the mounting parts out of aluminum.

I'm cheating and doing a fairly close copy of Blondihack's install:

Her video describes the process and parts more completely, but the quick summary of the mounting parts is:

1. I may use a block at each end of the long scale between the lathe and scale as I need a bit of space to clear some raised bosses. I might be able to use washers, but I'd like to have a place at each end to mount the scale and a cover w/o Swiss-cheesing the lathe with multiple holes.
2. There's an L bracket to mount the optical read head that bolts to the saddle.
3. On the cross slide, I'll need to support the magnetic read head with a block to elevate it over the carriage a small amount.
4. Also on the cross slide, I'll need to extend the slide portion beyond its back by about three inches (because the read head mounts on the back side of the carriage).

I have a CNC mill (printNC) and can mill T6061 just fine....but to date I have not done any steel machining. The printNC can do steel, but I'd need new stock and new mills.

Is it OK to mix aluminum and cast iron for something like this? Most (but not all) of the lathe surfaces are painted which should minimize the opportunities for electrolytic corrosion. Most of the steel (12.9) bolts go thru clearance holes in the aluminum and thread into the lathe.

 

[RJSakowski]

Unless you are situated in the tropics, you won't have a problem with electrolytic corrosion. I sued aluminum mounting for all the DRO installs that I have done.

 

[rronald]

Unless you are situated in the tropics, you won't have a problem with electrolytic corrosion. I sued aluminum mounting for all the DRO installs that I have done.

Good to know.

I also realized two things after posting the original question:

First, I could 3d print the mounts. All the ones in compression (i.e., the spacer blocks) would last many years if not decades. The L-bracket might work as a print, but it would need to be thicker than a metal solution. I'm trying to get back into machining though...and that would be a minor surrender. But if I don't have the correct raw stock, it will be tempting.

And second, I suspect the scales themselves are aluminum bodied. So there's going to be aluminum touching cast iron regardless.

RR

 

[Eddyde]

Aluminum is fine, I used it for all of my DRO installations. It would be interesting to see how printed parts work. Please post pictures of your progress.
Here's how I mounted the DRO on my mill:

Dro Install On Mill *Updated*

Hi All, I was going to wait till I have all three axises installed before posting this project. However, with all the recent inquiries about these Chinese DRO kits, I figured I would be best to post what I have done so far. I bought a Easson DRO on AliExpress the end of last year. The...

www.hobby-machinist.com

[How-To] - Mounting a Z axis DRO on a Bridgeport (Clone) Quill

Hi All, A few years back I completed the DRO installation on my mill by adding the Z Axis to the head, that is my mill is a bed style where the head raises and lowers not the knee or table. However, I found it not be as useful or at least user friendly as I thought, mainly due to the fine...

www.hobby-machinist.com

 

[BWS Arms]

I would print them since you have the capability to do so.

 

[RaisedByWolves]

Is it OK to mix aluminum and cast iron for something like this? Most (but not all) of the lathe surfaces are painted which should minimize the opportunities for electrolytic corrosion. Most of the steel (12.9) bolts go thru clearance holes in the aluminum and thread into the lathe.

How long you planning on being at sea?

I’ve seen everything but plastic used for this with no issues.

Imo, this is not a situation where I would use 3D printed parts. When the parts fail there’s a good chance it will ruin your scales.

 

[rronald]

I did build a 14,000 lb boat in my yard. I avoided electrolytic corrosion by using bronze for almost all the hardware. But I'm pretty sure a cast bronze lathe would be at least 10x the price of a cast iron one. And not as good.

There are places where plastic is very unsuitable. But you can build significant portions of machine tools with it, if you design for it. My printNC (a CNC mill) is a mix of steel, cast iron, MDF, plywood, and ABS plastic. I can machine with ~.01 mm tolerances across an 18" x 38" area. ABS printed parts are used to hold ballscrews ends and the NEMA 23 stepper mounts. Some parts are suitable for plastic, some are not. For example, once the CNC was up and running, I replaced the ABS plates that captured the ballscrew nuts with aluminum (the plastic flexed too much).

Many, if not most, 3d printers have many 3d printed parts. Plastic is significantly lighter than most other options (which allows higher acceleration rates). The one I built in 2020 (a VORON) is over 3 years old and is still considered one of the best printers available.

I'd estimate that a properly 3d printed spacer block of ABS with almost zero load between a scale and the back of the lathe would last at least a decade or two. I feel compelled to do at least a few parts that way.

 

[jwmelvin]

My x-axis read head is mounted to the saddle with a printed bracket and has been perfect for two years so far. I believe I used PLA.

 

[dabear3428]

IMO printed parts are fine, if you are loading any of these parts enough to matter something else is wrong.

 

[u2fletch]

Here is my installation on a LMS Hi Torque 7500 lathe. Glass 1um scale for Z, Ditron 1um mag scale on X. 3d Printed parts to mount the sensors. Also 3d printed brackets to mount the tablet.