Advice: Drill stainless front for anti-vacuum drain

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
BenS
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#1: Post by BenS »

Hi There,

My anti-vacuum valve is gone so thought I'd upgrade to one which drains to the drip tray but this requires drilling the stainless steel front (and metal backing) so thought I'd ask for advice on doing this.

I'll be using a hand-held drill and the Youtube 'experts' suggest:
- Using a low speed
- Don't use oil, use water in a spritzer bottle (plus it's easier to clean-up)
- Tape the area and mark the hole with a punch
- Start with a pilot hole using a 3mm bit
- Use multiple bits going up in size until desired size is reached
- Be patient!

Obviously I don't want to ruin things so confirmation of the above plus any corrections/suggestions welcome.

Cheers, Ben

Marcelnl
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#2: Post by Marcelnl »

What diameter hole do you need? If it's large and if you can access the plate why not buy a punch? Drilling a largish hole with a handheld drill in plate material is a challenge and given that it'll end up being in sight you want it to look clean. It's surely possible with what you describe but drilling in (thin) plate material carries the risk the drill end 'snags' and the torque of the machine warps the plate.
Hand drilling multiple holes in increasing diameter by hand never worked for me.

https://www.conrad.nl/nl/p/wolfcraft-37 ... 68330.html

Or a multi diameter plate drill if the hole is not that large.
https://www.manutan.nl/nl/mnl/multi-dia ... KsQAvD_BwE

Try finding a friend with a drill press if you're drilling , you only need it for a few minutes.
LMWDP #483

BenS (original poster)
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#3: Post by BenS (original poster) »

Thanks for the reply,
Marcelnl wrote:What diameter hole do you need?
It's around 9.5mm - for the barbed->BSP elbow fitting.

Marcelnl wrote:If it's large and if you can access the plate why not buy a punch?Drilling a largish hole with a handheld drill in plate material is a challenge and given that it'll end up being in sight you want it to look clean. It's surely possible with what you describe but drilling in (thin) plate material carries the risk the drill end 'snags' and the torque of the machine warps the plate.
https://www.conrad.nl/nl/p/wolfcraft-37 ... 68330.html
Wow, never seen on of those, is it called a punch in English?

So you just screw it with a wrench and it makes a hole? Certainly looks safer then drilling.

My machine has a thin piece of polished stainless sitting in front of what looks to be 2-3mm black steel (not sure what metal type it is). I was hoping to drill from the front through both metals to get a more accurate hole but maybe this will be more difficult than I thought?

I'm not sure the black metal is easily separated from the bottom frame (which is made from the same black metal) so should check this.

Marcelnl wrote:Hand drilling multiple holes in increasing diameter by hand never worked for me.
Thank you, good to know people's real-world experiences.

Marcelnl wrote: Or a multi diameter plate drill if the hole is not that large.
https://www.manutan.nl/nl/mnl/multi-dia ... KsQAvD_BwE
I have a stepped bit like this, I used it to drill my webber BBQ. So this would be easier than a standard drill bit?

Marcelnl wrote:Try finding a friend with a drill press if you're drilling, you only need it for a few minutes.
I do have a drill press but I'd have to disassemble the entire machine to get it on the press, so was hoping it could be done from the front.

First things first, I should check if the front black metal plate can be easily separated from the bottom frame - right? Because this will determine if I could use the drill press or not.

Thank you for the advice, glad I posted first - very much appreciated.

Cheers, Ben

JRising
Team HB

#4: Post by JRising »

I would suggest getting a couple of titanium twist drill bits to cleanly handle the stainless steel.
If possible to drill from back to front first, use the smaller bit to go back to front. The softer steel will be easier to start through and will steady the drill bit when it makes it to the stainless and has to the difficult part. Once that hole is through, then go front to back with the larger bit (the size of your silicone hose) so that the face of the machine is cut clean and round.
That's my 2 cents worth. I once had to drill a half-dozen stainless steel laundry chute doors.

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cafeIKE
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#5: Post by cafeIKE »

With this style vac break.



and a couple of plumbing parts



The area around the vac break is 15 years of daily use and the rest of the machine is like new



No need to drill. SS is a nasty PoW.
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ira
Team HB

#6: Post by ira »

If you really want to make it easy, try to find a shop that caters to machinists. The difference between the drill bits you buy at a local shop for homeowners and what you can get if you're serious about machining is like night and day. Gold coating on cheap steel is OK for wood and aluminum, but not so much for stainless. Also, back up the hole as the bit will grab hard when it goes through and you probably don't want to hit what's behind it. Also if you can get a clamp to clamp the 2 pieces of metal tightly together, get 2 more pieces, one in front to guide the bit and one behind so you don't break through. Use a proper cutting fluid. And if you can clamp, make the hole in the front piece on a drill press so it guides the bit in straight. Do all that and you should have no problem. If you just have to drill free hand through 2 thin sheets of metal, it might not turn out so good. A small starting drill followed by a step drill would probably be the best solution in that case.

Marcelnl
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#7: Post by Marcelnl »

many drill presses can swing left and right, won't the machine fit?
Using another type of vac valve is also a good option, further; what Ira said!
LMWDP #483

BenS (original poster)
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#8: Post by BenS (original poster) »

Thanks for all the excellent suggestions. The black metal is folded to form the front so it can't be removed.
JRising wrote:I would suggest getting a couple of titanium twist drill bits to cleanly handle the stainless steel.
I do have a tungsten carbide bit which I'd planned on using - should've mentioned that earlier.
Marcelnl wrote:many drill presses can swing left and right, won't the machine fit?
Excellent point, thanks for reminding me!
ira wrote:Also, back up the hole as the bit will grab hard when it goes through and you probably don't want to hit what's behind it. Also if you can get a clamp to clamp the 2 pieces of metal tightly together, get 2 more pieces, one in front to guide the bit and one behind so you don't break through. Use a proper cutting fluid.
Excellent suggestions, thank you. So would a softer metal like aluminium be a good choice for the front and back clamping or is steel better - or does it not really matter with if using a drill press?

I also found some cutting/drilling paste in the garage - is that what you meant by 'proper cutting fluid?' I have the 250ml can: https://www.crc.co.nz/CDT-Cutting-Range ... 3e9fde48d/

Based on the suggestions...
- Clamp the stainless front to the black metal
- Clamp aluminium front and back of hole site
- Drill from the front using a drill press to one side + carbide bit
- Use metal cutting paste on bit
- Go slowly
- Regularly spritz water just to be safe

Does that sound like a good plan or have a missed something?

Cheers, Ben

BenS (original poster)
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#9: Post by BenS (original poster) »

Sorry, my drill press won't swivel - I tried to delete the previous post after writing this one but I can't (nor can I delete this one) so sorry for any confusion created.

I'm thinking a safer option might be to remove the stainless cover and drill that on the drill press, then reattach, and drill the softer black metal from the front with the hand-held drill. The stainless is 1mm, see attached.

If so, any tips for removing the head, gauge (and electrics) from the front would be welcome. I have limited experience but I did replace the original steam valve with a lever so understand that because everything is brass, it's easily damaged if overtightened etc.

Thanks for the advice, have just made a donation to the site for all the help so far. Cheers, ben


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cafeIKE
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#10: Post by cafeIKE »

You could run the hose into an espresso cup in the machine. The tiny amount of water out of a vac break will evaporate. Clean the cup when you descale.

Don't over think it