My new machine - Guess the make!

[Pilsbury]

Steve P who has commented on one of my end grain inlay chopping board videos on Youtube was asking for some info on my settings. He's on this forum so I said I'd post my workflow on here as opposed to a lengthy post on Youtube comments.

I watched tons of the inlay videos, but never found a totally comprehensive tutorial. I just ended up getting a bit of info here and there to work out what was actually going on, refined it a little, then made some stuff up myself!

So, first off get your design and load into Vectric or whatever your using. You'll make the pocket first. Save this as "pocket".
Now mirror this design to flip it and save as "plug". It's important you don't resize any of these 2 designs now.
Go back to your pocket file and run a v carve toolpath. I use a fine tapered ball nosed end mill something like a 0.25mm radius tip with a 5^ side angle. You can also add a clearance tool which will save loads of time. I just use any old end mill, basically as big as I can get away with to remove the bulk of the material. Often this is a mere 2 or 3 mm as otherwise on fine designs, nothing is removed
I cut this pocket to a depth of 8mm in 3 passes. Generic speed and feed for me is 18000rpm and 2000mm/min in the hardwood. Not sure why, but it works fine!
You'll find there are a fair few fuzzies and blocked carvings that need to be faffed and picked out with a blade and air gun

Now for the plug in a contrasting wood. open up your saved plug file and drawer a boundary around the design. This is so when you run the toolpath, this immediate area is hogged out and it also serves to throw the plug cut with a relief inverse to the pocket. That boundary is also for when its finished so you can cut your plug out of the rest of the wood.
Again select v carve toolpath and use the same bits you used on the pocket cut.
Now here is the bit that warped my mind - flat depth and cut depth..... You need to have a glue gap at the base of the mating surfaces. You also need a bit of gap at the top of the mating surface to cut or mill off. Plus this will let you press the 2 parts together without grounding out. I have used 1 mm glue gap and 2 mm top gap. Another part of this mental torture is that you have to use a few set cuts or the machine will not realise where the top of the material is..... God, I'm not explaining this well - so here are my toolpath depths:

first pass 1.5mm (d), 2mm (f)
second pass 4.5mm (d), 2mm (f)
third pass 7mm (d), 2mm (f)

This results in the plug being the inverse of the pocket. Same applies to cleaning this up, pick out the bits and fuzzies with a razor blade.

Check they mate well, then glue up. I use titebond 3, but any pva type glue will probably do. That titebond recons its waterproof and food safe. Plus the yanks love it so it must be good.

Don't go too heavy on the glue, just ensure all parts of the sides of the pocket are covered. don't leave massive pools of glue in the pocket for 2 reasons. Firstly, the glue might not escape and wont let you press the plug in properly. Secondly which is a real bummer, having a load of wet glue sitting there and soaking into the wood causes warping. I've had several boards properly banana on me from having glue saturate the one side straight in the end grain.

Once the pocket and plug are mated, squeeze the life out of them. So many youtubers show them tapping together with a rubber mallet and there is a massive gap between the 2 pieces. Then, Lo and Behold, when they bring the dried piece back into shot to mill flat, the gap is all but gone and the 2 pieces are snug. Took me ages to figure this out but I assumed this must be a hydraulic press although never saw one being used. Clearly a trade secret unless I'm barking up the wrong tree. So I made one as you can see in the youtube video with a bottle jack.

That's pretty much it in my own garbled way. Ask questions if you want or need to. And for the experienced CNCers, please comment on my workflow. I'm a relative amateur who has plucked all of this from youtube videos and fudged my way through trying to interpret what people are doing without them telling me!

[didineedthis]

Cheers Mark,
Will defo help me when I attempt my 1st Inlay.

Now here is the bit that warped my mind - flat depth and cut depth..... You need to have a glue gap at the base of the mating surfaces. You also need a bit of gap at the top of the mating surface to cut or mill off. Plus this will let you press the 2 parts together without grounding out. I have used 1 mm glue gap and 2 mm top gap. Another part of this mental torture is that you have to use a few set cuts or the machine will not realise where the top of the material is..... God, I'm not explaining this well - so here are my toolpath depths:

first pass 1.5mm (d), 2mm (f)
second pass 4.5mm (d), 2mm (f)
third pass 7mm (d), 2mm (f)

This results in the plug being the inverse of the pocket. Same applies to cleaning this up, pick out the bits and fuzzies with a razor blade.

This is a good video that explain the gap in detail.
https://www.youtube.com/watch?v=l4VMo9DCzO8

and another by the 'Two old guys'
https://www.youtube.com/watch?v=WYnO8kSHQ1c
Top Man