Quote Originally Posted by Dylan View Post
I have zero expertise drilling ceramic, but is it possible to have a jig for the drip trays that would allow them to be flipped, you could then drill half way from each side to prevent the exit 'wound'.
The problem with a jig is that each ceramic piece has shrunk and warped ever so slightly differently, making hole alignment difficult. However, we’re going to try a two step process, by first drilling a centering hole, so that we can then try flipping the drip tray around and doing what you suggest.

Quote Originally Posted by Dylan View Post
Does the drain point sit proud of the base of the drip tray? As this will mean that not all the water will drain, and much like in a non-drained drip tray if its left in there for a few days it will go a bit skanky. The little gaps around the exit point will also develop mould that will be a bit more difficult to clean out. I imagine it would be more difficult to achieve but an exit point that was flush with the base would be more desirable... could something be glued on to the bottom that didnt poke through?
It sits about 2mm proud. We’ve been trying to make it as level as possible, but it will nonetheless behave like a kitchen sink drain sieve, with gunk accumulating on the edges.

FWIW I’ve never seen an espresso drip tray, plumbed, that didn’t need periodic cleaning. Even if the drain was totally flush, the problem is that if you throw espresso shots into the drip tray, the coffee particles will settle in place and slowly accumulate.

For me, the goal of a plumbed in drip tray is to make cleaning much less frequent, but it’s not possible to remove the need for cleaning, given the muddy quality of coffee.

I’ve seen some pro machines with the tube intentionally lifted off the bottom, so that just water goes out the tube, and solids accumulate on the bottom. The reason for this, I assume, is to keep the tube from getting clogged with coffee mud.

With the two group E61 we have, the drain is flush, but we have to periodically disassemble the drain tube because mold eventually grows on the inside of the tube, feeding on the coffee deposits.

Quote Originally Posted by jdomg View Post
Can you link the drill bit you are using? The picture is too low res to tell if it's a solid or core bit.
here it is.

Quote Originally Posted by jdomg View Post
Additionally - there are a few guides on line for each, but I suspect you were using a solid bit and the chipping on the back end was due to applying just a bit too much pressure towards the end. One way I've avoided something like this (though I have no idea if it's a standard thing) in the past is to drill a super small pilot hole clean through which will have a little bit of chip and then "score" both sides with a core drill bit. Since you have a smaller pilot - you can setup a jig that aligns the drill press with the hole as coring bits that size usually don't have guide bits.
Someone else also suggested this approach, and I think it’s a good idea. We’re going to try it today.

Quote Originally Posted by jdomg View Post
So... you pre-drill a small pilot, swap the bit for a core bit of the correct size, drop it in a little to score off the enamel and "break" the edges cleanly (but not all the way through) then flip the tray over and then drill clean through. This *usually* works pretty well for both sides being clean. You can also apply some masking tape to the drill area to help as well. Plus your wood block on the back should help minimize ugliness on the exit.
Thanks for the more extensive tips, all very useful.

Quote Originally Posted by xpresso View Post
What is required to prevent break out on drilling through the likes of ceramic is full surface support at the break out side, the ceramic surface will not be uniform or totally flat so timber would have a very limited success, apply a strong adhesive tape to the break out side area and place a piece of stiff rubber to help that support, we called that material 'insertion', it was bordering the same stiffness of a rubber tyre composition and has a woven reinforcement sandwiched within, we used a thickness of about 6/8mm and purchased in a roll.
Great, will do. We have a variety of sheets of rubber and plastic here that I can try.

Quote Originally Posted by xpresso View Post
I have used it successfully in the past to drill holes in plates for clock mechanisms, I even tried with success using a cataloy paste spread over the break out side and then laterally tap the residue off when finished, the latter is time consuming, the drills I used were the cheap diamond dusted ?? hollow drills from China.
I suspect you were using the same bits we’re using.