Thread: Sacrificial Milling Plate Material

I intend milling with 4-5-6 mm end mills some 10 mm CI disks clamped directly on the table.

What I need is a relatively thin (say 2 mm) sacrificial plate that will be partly machined by the tips of the end mills.

As I believe the sacrificial plate should be softer than the work, I have aluminium, PVC and brass available.

Looking for comments on the advantages and disadvantages of these materials, or suggestions for better alternatives.

John.

If it were me, aluminium definitely. Brass = $, pvc may not compress equally and so allow the work piece to tilt.



-russ

Hi John,

I agree, aluminium is perfect. I made a false table from 12 mm plate to do just that. Easy to drill and tap holes exactly where needed. I originally used 3 mm alloy plate and the "T" slot bolts with clamps, but found that I couldn't always get clamps in the best place.

MDF or HDF

MDF -- can't say I have tried that.

Dunno if I would like to put it on mine with coolant and all. And wouldn't the "swarf" go to dust, come sludge??

Thanks to all, aluminium it is, I have some 3 mm which will be perfect for this job.

BaronJ,
Yes, I think a thick plate like yours could be very useful.

John.

Originally Posted by 12bolts

MDF or HDF

Mdf is really good if you are machining dry. With coolant it turns into a soggy mess that is hard to clean up.

John I don't know why you feel it's necessary to have the sacrificial softer than the work, it really won't make any difference.

What you use is largely a matter of what you have available and the tolerances you need. Wood is fine if the tolerances aren't tight. Aluminium/acrylic/steel/cast iron/etc if the tolerances are tighter. In the latter case it's easier to use a piece considerably larger than your work, fix it down to the table, and then give it a light skim with a fly cutter or large end mill. Thicker material will make that job much easier. Your sacrificial table is now as accurate as your machine can mill. Then clamp your work down to this new "table". A lot of people make fixture plates specifically for this purpose with tapped holes, especially for clamping down small work, I've heard them called "mini-pallets" so you can look that up if you like. A small pallet like that has been on my list of jobs to make for a while now, and of course the same principle can be taken as large or small as you like.