Drilling large number of holes in 1.2mm stainless

[19brendan81]

Hi guys,

I need to make a piece of equipment for brewing. Its esentially a custom pot, with a large number of small holes (1 to 2 mm) drilled in the bottom. this custom pot holds crushed grain and water inside another traditional pot at approx 65 degrees for an hour, and is then lifted up so the water can drain into the traditional pot and the grain remains behind.

I got a piece of fine stainless mesh off a fellow forumite last year for this project but the weave was too tight and clogged. Commercial products exist that would be perfect (stainless perforated mesh) but getting an offcut the size I need is proving difficult (I need a bit 450mm square) and buying whole sheets is very expensive.

So - im considering making my own piece of perforated mesh from some 1.2mm stainless sheet I have at home. My question is - what do you think the best way of doing this would be? Using a traditional drill bit and being patient - or could I creart some sort of punch that would do the job for me with a good solid blow? I estimate I will require at least 200 2mm holes.

Brendan

[Graziano]

What's the volume of this pot?. I'd be inclined to check out a commercial kitchen store for something stainless used to boil and strain spuds or alternatively get some mesh offcuts from a plumbing sheetmetal shop.

[pipeclay]

I would think unless you have a mechanical press the punching method would be very hard to do.
You would also need the die and a bottom plate on the plattern to stop the sheet from bending.

You would also need something with an opening big enough to accomadate your sheet or at least to be able to cover more than half.

I dont think a swing press would do it unless it was 3 ton plus.

If the finished appearance/shape is not important you could try a large centre punch (the type boiler makers use) and hit this with a block hammer to push a hole through your sheet.Once again time consuming and would look overly good.

I would say you would be better off to get your self a few of the correct size drills and cutting compound and drill them,should take much more than 1 hour to drill and a little bit more to chamfer.

[19brendan81]

The commercial pot that I own to hold this custom one is 71L (450mm diameter). The cusom one will be made slightly smaller (425mm diameter). the prob with commercial strainers for pasta, spuds etc is the perforations are far far too big (5mm or 10mm). I need 2mm perforations max.

[.RC.]

I would drill them...200 holes is not many...

I have heard of panel drills which are drills suited for sheet metal work....

[Dave J]

+1 to what Pipeclay and RC said, I would just drill them.

Dave

[Jarh73]

Several years ago I had to make Teflon discs into filter paper holder for some stack (read industrial chimney) testing equipment.

Disc were of various sizes the biggest being 100mm diameter.

I simply got a small off cut of SS mesh and mounted it onto the Teflon disc with a single bolt in the middle and then drilled all the holes through the mesh with a drill press. So easy I ended up getting my wife to do it.

The Teflon filter holders looked like they were made by a machine that is how well they turned out.

I would suggest doing the same thing for your application.

Just get a smaller piece of mesh as a guide and move it once you have done all the holes in a area.

Also you can now get cobalt double ended rivet/panel drill bits.

Cheers

Justin

[Jekyll and Hyde]

Don't know if you can get panel drills in 2mm, usually they're around 8mm... and I don't know that you'd need one for holes that small? :?

A trick to make a standard drill bit work better on sheet metal is to sharpen them with a large included angle (ie. cutting edges closer to parallel), tends to make them less likely to grab as they break through. Again, don't know that it would make much difference on a 2mm hole, and I hate sharpening drill bits that small, I go crosseyed...

[Jarh73]

Don't know if you can get panel drills in 2mm, usually they're around 8mm... and I don't know that you'd need one for holes that small? :?

A trick to make a standard drill bit work better on sheet metal is to sharpen them with a large included angle (ie. cutting edges closer to parallel), tends to make them less likely to grab as they break through. Again, don't know that it would make much difference on a 2mm hole, and I hate sharpening drill bits that small, I go crosseyed...

You can get 3mm panel drills. Good point might not be able to get in 2mm.

Mind you 2mm drill bits are cheap so buy a handful at a time.

Cheers

Justin

[Michael G]

My advice is coolant. Stainless will work harden and the drill bits will go blunt really quickly. I think the best thing to do would be to put the piece you are drilling in a pan of water/ coolant so that you are drilling 'underwater' - that way the drill is not going to get too hot (That is, pan of water then block of timber then item being drilled, so that the item being drilled is a few mm under the water surface).
If that is too complicated, use a squirter bottle. However, as soon as that bit goes blunt you are in trouble. You can't be nice to stainless with light feeds and shallow DOC. Your cutting tool must basically cut out the SS that has started to work harden the next time around.
I'd also be using a stub drill for rigidity.

Michael

[rusty steel]

I'd be looking for a piece of mesh Check with sheet metal fabricators. I they don't have anything they may be able to suggest another source. Better still, drink milk.
Russell

[Stustoys]

Hi Brendan,

Are you sure 200 holes is going to do the job? Thats the same as one 14mm hole.
Anyway thats not my problem :)

Drilling by hand normally stops work hardening issues, though I dont recall hand drilling any 2mm holes.

You should be able to punch a 2mm hole in 1.2 SS with a Whitney punch, the smallest punch I could find on a quick search was 3/32"(2.4ishmm) close enough?

Roper Whitney 5 jr and XX Hand Punch at Van Sant Enterprises, Inc. (http://vansantent.com/Hand_punch.htm)

Stuart

[Ueee]

Hi,
I own a Jr and a XX whitney punch, and although it would work fine, you would probably go through several punches and of course not get to the middle of the sheet.
I would go one step beyond a stub drill and go with a center drill. This way there is very little chance of breaking the drill and the top side of the holes could be de-burred with the one process. I'm not sure what gear you have, but if you want the use of my HM50 with coolant just PM me.

Ewan

PS, how did the cordless drill go for the lifting device?

[19brendan81]

Thanks for all the input fellas.

Re 200 holes being enough...I am now having second thoughts as I did the maths too and I think theres a real risk they will block or flow too slowly.

I also agree that a center or stub drill would be the way to go.

Thanks for the offer for the Mill Uee, one of the other local machinists has offered the use of his CNC machine to do the job for me which will be a massive help. Its a very generous lot on this forum.

Brendan

[John H]

Hi Brendan,

I'm not sure how many holes are in this but this is what 10mm spacing of 2mm holes would look like on your 425mm disc.

Would you want more or less?

[Stustoys]

Hi Brendan,

If you are going to use a mill and depending on the height of the sides of your pot. Couldnt you just drill the bottom of the pot?

Stuart

[19brendan81]

Gday John - I reckon that would be perfect. How long would it take your machine to do that do you reckon?

P.S Stu - what I am making is a custom strainer to fit within a pot, John has kindly offered to assist with the machining of the bottom for the strainer. If I drilled my current pot it would indeed become a strainer but then I would need to make a bigger one to hold it! The concept is the same as using something like a pasta cooker like this...

http://cngoodsteel.en.made-in-china.com/product/honJzONVLScX/China-201-Stainless-Steel-Pasta-Pot-MSF-795-.html

..only the small size of the grain used in brewing means the holes in pasta pots are way too big.

Brendan

[Stustoys]

Sorrry Brendan I've been partly missunderstanding what you were trying to do. I thought you had the two pots and were going to cut a hole in the bottom of the inner one to take your s/s with 200 holes in it. Thats why I thought Whitney punch would reach as the piece of s/s to take 200 holes wouldnt need to be very big.

There will be 133ish hole in the outside circle alone. Great job for a cnc punch press. Pitty I dont have access to one anymore.

Stuart

[John H]

I've never played with stainless steel so I'm not sure on speeds and feeds.

If flood coolant is a must, I'll need rig up pan/enclosure so I can use the coolant setup off my mill. This is a job I have on my to-do list anyway.

Once everything is all setup, its a good time for a cuppa while the job runs.