surface grinding copper

[monqy]

Hi, I'm new to the forum and watercooling in general, but I have considerable experience with machining and I'm toying with the idea of making my own block. I plan to surface grind the base, but I have never ground copper before. Are there any special precautions necessary for grinding copper? Can I even surface grind copper? Do I need a different wheel for the grinder?

I did a quick search on the forums and google but wasn't able to turn up anything specific.

Thanks!

[JFettig]

I have wondered about this, The only thing that I recall is that I havent really heard anything about surface grinding anything but steels. If I remember, Ill ask a guy at work tomorow.

I would guess that it doesnt grind well, mainly because its gummy.

Jon

[Brians256]

I thought that most people used a fly cut of the base, trusting the mill's XY axis to keep the base flat. Is surface grinding better at producing a flat base?

[jaydee]

Originally Posted by Brians256

I thought that most people used a fly cut of the base, trusting the mill's XY axis to keep the base flat. Is surface grinding better at producing a flat base?

Depends on the process. If you use a LapMaster for the surface ginding then you will have a very flat base. If you use a hand grinder and a stock grinding wheel you will get a terrible finish.

[agiacobbi]

Originally Posted by JFettig

I have wondered about this, The only thing that I recall is that I havent really heard anything about surface grinding anything but steels. If I remember, Ill ask a guy at work tomorow.

I would guess that it doesnt grind well, mainly because its gummy.

Jon

We used oil on copper when we surface ground it.
I forgot gotta use a soft wheel, like you use for carbon for electrodes

[SlaterSpeed]

- I tryed with a steel grinding wheel- it didnt work too well
- Cant try with a softer wheel as i dont have one but It should be possible.
- Best to grind with a vertical grinder IMO

@ Brian - Surface grinding produces a much flatter surface, with out the machining marks accosiated with milling cutters. Much like hand lapping only its guarenteed flat.

@Jaydee - Hope no one on here is that stupid, What exactly is a LapMaster?

slater..

[monqy]

Is there a certain make/model grinding wheel that is proven for use with copper? What grit should I buy...highest one I can find?

agiacobbi...what type of oil did you use? All I have access to is omicron machining oil. I know lubricants can get expensive really quickly so I'm not really looking forward to buying special oil.

[bigben2k]

http://www.lapmaster.com/single_sided.htm

[jaydee]

Originally Posted by SlaterSpeed

@Jaydee - Hope no one on here is that stupid, What exactly is a LapMaster?

slater..

As Ben pointed out they are used to grind precision flat cerfaces. Suprised you have not heard of them. All machine shops should have one.

http://www.lapmaster.com/lapping_polishing_machines.htm

[SlaterSpeed]

Yeh ive herd of them. Never seen one tho :shrug:

They look a bit expencive for me

[bigben2k]

eBay sometimes has them. Still pricey though.

[jaydee]

Originally Posted by SlaterSpeed

Yeh ive herd of them. Never seen one tho :shrug:

They look a bit expencive for me

I wasn't very serious in that comment. They are somewhat expensive and don't really have much use in a regular machine shop. Would love to have one though. Would be good to make flat bases on water blocks.

[2Shane]

Surface Grinding of copper...

Easy. Use a solid metal wheel - a dead soft aluminium, and a hard and fine compound - such as a automotive valve lapping paste for a fine finnish.

The hard material embeds in the aluminum, and this grinds the copper away.

Use a mix of lubricants, a deodorised kerosine ~ 10 - 15% for a thinner, and a boundary lubricant such a lard.


If your doing this commercially, use a bottom sucking recirculating pump, to keep it all cool and the abrasive in suspension.

For a 1 off, get your copper block flat, with hammer or lathe etc., and get some 6mm or 1/4" dead soft pure aluminium sheet ~ 30cm x 30cm, some thicker cloth such as felt or windcheater material to carry the sheet and some chip board to carry the lot; then use some automotive valve grinding paste, then rub the copper block in small circles over the entire glass area, and then slowly rotate the copper block to eliminate any abberations caused by uneven finger pressure.

This will bring it up a treat.

If you can't get dead soft 6mm or 1/4" aluminum sheet; some plain kind of fiberboard will do fine.

[qet77]

I am not done with by homemade block yet, but I did start finishing the block that I am putting between the TEC and waterblock and this is the first time I have made something that actually has to be really flat. Maybe the mill I used kinda sucks but the fly cutter didnt leave it totally flat I found out when hand lapping. I dont know about grinding it but generally with copoer you need a very high cutting speed. There is a grinding machine at our machine shop but I dont really know how to use it.

[2Shane]

Yeah - copper is not funny stuff, if it's treated as copper, instead of steel.

I guess it's all a matter of intent and worth. If your only doing a 1 off.. the ende doesn't really justify the means, so getting "all the secial tooling" specifically for soft or hard copper seems pointless and expensive.

But with things like fly cutters, having your High Speed Steel (HSS) cutter properly profiled and sharpened to the correct form is pretty easy and inexpensive.

I am not real sure of the best cutter profile - but the optimum set up for a drill, makes an enormous amount of difference, compared to a drill set up for steel.

The comparison.

Steel:

Helix Angle 27*, Point Angle 118*, Lip Clearance 8-12*

Soft Copper:

Helix Angle 30-35**, Point Angle 100*, Lip Clearance 12-15*

So aside from things like the helix angle (spiral of drill) the rest is quite changeable.

BUT these figures will give you a good starting point when configuring a fly cutter.

I'd also be inclined to put in a point radius, that slightly exceeds the feed rate, which correlates with the rake of the cutter, set for copper.

With this set up, you ough to be able to take it to a near mirror finnish, on your first pass.


Here is a piccy of some holes I had to drill through copper connectors I was making.

The NASTY burr, is from a slighlty blunt drill, set for steel; the really neat and virtually burrless hole is from a drill that was sharpened to a Point Angle of ~100* and a Lip Clearance ~15*

[ataxy]

Originally Posted by jaydee

As Ben pointed out they are used to grind precision flat cerfaces. Suprised you have not heard of them. All machine shops should have one.

http://www.lapmaster.com/lapping_polishing_machines.htm

well it all depends on what you are machining i used to work for a bridge crane company as a machinist and i can assure you there where no need for lapping machine there

[jaydee]

Originally Posted by ataxy

well it all depends on what you are machining i used to work for a bridge crane company as a machinist and i can assure you there where no need for lapping machine there

Yeah, If the parts are within tolerance then no point.

[Dukemurmur]

i asked this question to a machenist a while ago...he told me that most Cu is to soft and just clogs the wheels the best thing to do is to take a pass with a HIGH quaility carbide facing cutter then lap it by hand on a granit block...

BTW dont mind my spelling i am a little hungover

duke

[Brians256]

Hand lapping is fine for lower tolerances. But, unless you have an exceptional hand, you tend to get rounding. Now, that rounding isn't 1/8" or anything. But, it is significant for our realm where we are trying to mate two surfaces together. Bill had some good posts on this subject. Look for "hand lapping" or similar terms and search our forums.