Yet another epoxy granite mill

[peteeng]

Hi Ard - When you have steel grit blasted if its a humid day it can flash rust in minutes or hours. So you need to surface coat it asap to stop this sort of rust. Peter

[badhabit]

Coating in epoxy sounds like a good option.

The manufacturer of the epoxy don't recommend epoxy-on-epoxy without roughing up the surface. So i don't think i'll be doing that. However, i saw (and touched) a part that was first sandblasted and then metalized with zinc in their "hot sprayed process". It was like touching grit 180 sandpaper! The told me that paint sticks extremly well to this surface, so i think i'm going for sandblasting + mild metalization. I'm convinced that the EG will get a very good mechanical grip into the surface...and i don't have to worry about the rust...

The only "teoretical concern" i have is that i'll be having a zinc layer between my steel and the EG...i'm not sure if it will have any (real life) impact on the transfer of vibrations...or the long-term binding of the steel/EG...any thoughts on this?

/Thomas

[peteeng]

Hi Thomas - One of my clients manufactures elevated work platforms for high voltage inspection work. Some of the structures like booms and jibs are made from pre-galvanised steel then wrapped in fibreglass. They use vinyl ester and epoxy resins in various parts. They have to be structurally and electrically tested every 5 years. I used to do the structural testing and observe the high voltage electrical tests. Some have been in service for over 20 years with no hint of issues so I expect the metalising will be fine for the mill. Peter

[the4thseal]

no it is not an oil. It is actually not a problem for coating or epoxies. It is used in the automotive industry before painting. https://holdtight.com/ check them out. I use their products. There are others, so this is a starting point for you. I am sure you get a handle on in.

[peteeng]

Hi T4S - Thanks good to know. And it removes blood stains really well apparently. Sort of an ammonia. Maybe Thomas can mention this sort of product to his blaster? Peter

[badhabit]

Maybe Thomas can mention this sort of product to his blaster?

Just dropped of the parts at the blaster. They didn't do that and i think they are the only blastingcompany in my local area, so i just went with the blasting + metalization....

[badhabit]

Just dropped of the parts at the blaster. They didn't do that and i think they are the only blastingcompany in my local area, so i just went with the blasting + metalization....

This is how they look now:


Next stop: The mould...

[ardenum]

You're gonna send it to machining after casting the parts? How much for that?

Was there any reason you went with hard way covers instead of maybe below covers with metal plates or full armored ones? or just preference?

[badhabit]

You're gonna send it to machining after casting the parts? How much for that?

Yeah, machining and grinding to the tolerance specified for the rails... somewhere around 5000usd for the entire thing...or rather, that is the estimate i got from the machineshop from my initial drawings...it can change :-)

Was there any reason you went with hard way covers instead of maybe below covers with metal plates or full armored ones? or just preference?

I just think it looks nice :-)

/Thomas

[ardenum]

Yeah, machining and grinding to the tolerance specified for the rails... somewhere around 5000usd for the entire thing...or rather, that is the estimate i got from the machineshop from my initial drawings...it can change :-)


I just think it looks nice :-)

/Thomas

I took a second look at your column, how are you going to align it with the bed to get 90°?

[badhabit]

I took a second look at your column, how are you going to align it with the bed to get 90°?

Originally i was going to put a small rod of e.g. copper between the two steel-plates. I could "squish" this with the mounting bolts for the column. By squishing either in the front or back i could tilt the column...

However, i changed my mind and added a series of adjustment bolts instead:

In between the M16 mounting bolts, there are M12 setscrews... i can use these to adjust the tilt of the column back and forth and side to side... Furthermore, on the side of the steelinsert in the bottom half of the base, i've added M12 holes on the corners. To these i can attach a small bracket with additional setscrews to rotate the column during alignment. I've drilled the M16 through-holes in the upper-half slightly oversized for extra "wiggleroom" during alignment... So i think i've got all adjustments covered(?) :-)

I might still use the copper-rod idea. But might switch to something even softer like rubber. This is to prevent the epoxy from getting into the mounting holes/setscrews when i'm gluing the top to the bottom half. If you look closely at the image above you'll see two extra holes in the middle of the top-plate. This is for small hoses that go outside the casting. When everthing is aligned and i'm happy with everything, i'm going to inject epoxy into the gap between the two plates via these tubes.

/Thomas

[ardenum]

In between the M16 mounting bolts, there are M12 setscrews... i can use these to adjust the tilt of the column back and forth and side to side...

/Thomas

Does this technique have a name or a guide/description somewhere?

[badhabit]

Does this technique have a name or a guide/description somewhere?

I don't know, but i don't think so. It just seemed like a good way to align the column with the base.... i guess i'll find out if i'm right about that or not ;-)

[ardenum]

I don't know, but i don't think so. It just seemed like a good way to align the column with the base.... i guess i'll find out if i'm right about that or not ;-)

I was hoping you knew, I've been trying to figure it out and no matter how much I think about it I don't see how it's supposed to work. After some though on the matter I came up with a different option where you use a half pin/half set screw. it should work. like this: lower part a pin upper a thread. as you screw it in the lower rotates and the upper thread lifts or lowers the top plate.




EDIT.

Now I get it, the lower plate must not have a thread and the top plate must have a thread, so the setscrew can rotate in the lower plate as you screw it in. Case closed.

[badhabit]

I was hoping you knew, I've been trying to figure it out and no matter how much I think about it I don't see how it's supposed to work. After some though on the matter I came up with a different option where you use a half pin/half set screw. it should work. like this: lower part a pin upper a thread. as you screw it in the lower rotates and the upper thread lifts or lowers the top plate.

But this will effektively be the same as i'm doing? The set screws in my setup will enable you the raise or lower the column. When one is satisfied with alignment, the big M16 bolts can be tightened, locking it in place...and then glued :-)

[ardenum]

But this will effektively be the same as i'm doing? The set screws in my setup will enable you the raise or lower the column. When one is satisfied with alignment, the big M16 bolts can be tightened, locking it in place...and then glued :-)

Yea, I realized. For this to work the bottom plate must not have a thread so that the setscrew can rotate freely and the top must have a thread so that it can lift or lower.

[pippin88]

??? I'm confused by the fancy screw pin. You don't need a hole in the bottom plate for the set screw.

Set screws with thread in top plate and no hole in bottom plate. Set screws bear on bottom plate.

Align by adjusting set screws.

Inject epoxy. Allow to set.

Tighten bolts.


You can use annealed copper wire or similar instead of set screws and just compress the wire as needed by the bolts. Align. Then inject epoxy.
See Stefan Gotteswinter "Tramming a milling machine with epoxy"

[ardenum]

??? I'm confused by the fancy screw pin. You don't need a hole in the bottom plate for the set screw.

Set screws with thread in top plate and no hole in bottom plate. Set screws bear on bottom plate.

Align by adjusting set screws.

Inject epoxy. Allow to set.

Tighten bolts.


You can use annealed copper wire or similar instead of set screws and just compress the wire as needed by the bolts. Align. Then inject epoxy.
See Stefan Gotteswinter "Tramming a milling machine with epoxy"

Thanks for clearing that up.

[peteeng]

Hi All - You can also use epoxy putty like this. The advantage is that it does not flow like a liquid. You can let the machine parts come together which squashes the material out, knife off the squeeze out and your done. Peter

https://www.selleys.com.au/products/...nead-it-steel/

[badhabit]

Set screws with thread in top plate and no hole in bottom plate. Set screws bear on bottom plate.

Align by adjusting set screws.

Inject epoxy. Allow to set.

Tighten bolts.


You can use annealed copper wire or similar instead of set screws and just compress the wire as needed by the bolts. Align. Then inject epoxy.

Exactly :-) I started with the copper-wire idea, but ended with setscrews as it gives me more options during alignment. But might do a sort of combo of the two.

I had planned the injection of epoxy into the design via the two tubes in each side of the column-feet. I also planned to use a special epoxy design for this task, it contains a large amount of very small steel particles. I've seen others use this, but i cannot seem to find it again. Does anyone know what type i should use and possibly where i could buy it(in Europe)...?

EDIT: Found it right after i posted the question: https://www.diamant-polymer.de/en/products/dwh/ (I'm considering the 310 FL)

/Thomas