How to machine hole on top edge of workpiece

[savarin]

clamp it to a thick sheet of wood on the drill press, use a 5/8" hole saw with the centre part that holds the drill bit shimmed to take a thinner drill, ensure the drill fits the hole already in the piece and passes through into wood, it should cut through with no problems at the open edge.
I have found starret hole saws squeal a bit but the others cut fine.

 

[Chipper5783]

Several options, all the suggestions above are good. If you use the “sandwich and drill” method, use a similar sacrificial material (I.e. not aluminum) or the bit will wander. If you choose to bore it (lathe or mill), then the material for the other half of the sandwich does not matter.

Pretty straight forward on the CNC. If it were me, locate the hole center (say X0, Y0), then a G176 or G177 - depending on the end mill size and if you drill a through hole first (only if your controller supports those codes).

Obviously the trick is to hold the part. Do not use the left or right end of the vise jaws - nearly all mill vises, the moving jaw will have a little bit of tilt (I can’t speak for all brands - just Kurt DX6, Kurt Anglock and PrattB HiLo - all are good kit). You can put an equal size piece in the other side (like when you are cutting a short piece in a cut off saw), better to use the mid point of the vise jaw. Then you will need a sacrificial pad, or hold the part about 60% sticking up - do half, flip it, do the second half. Or, here is your excuse to get some Talon grip jaws - set the teeth wide and come down to within a whisker of the jaw.

Let us know how you work it out.

 

[rronald]

It’s been a while since I watched James (Clough42) make his; here’s the playlist for the project:

Hemingway Sensitive Knurling Tool

Share your videos with friends, family, and the world

youtube.com

It's odd that my google-fu missed finding this (and also the Inheritance Machine video). It's quite helpful.

I think I'll play around with mounting the part about 3/4" above my fixture plate. I can then mount a sacrificial flat sided piece against that section (and prehaps under it too) so that the hole cut won't be interrupted:

• I'll see how that works with drilling form 6 to 8mm and if it's OK, I can step up to my largest drill that's < 5/8".
• If it doesn't drill well, I'll bore it out using a 12mm end mill.

With both of the above, I'll probably need to use a boring head......or move over to the lathe (or CNC)..... in order to get to the spec dimension.

 

[rronald]

I just bit on an ebay Criterion Boring Head: https://www.ebay.com/itm/156268062732

 

[rronald]

Success!

Moved over to fixture plate and mounted a short piece of 1/2" square bar beside the open hole on my part.


From the 6mm hole, I stepped to 9mm, then 12mm, then 9/16". It looks like the 9/16" was 5 or 6 thousandths over size, so I'm not going to use a 5/8 drill bit (for fear that will oversize the final dimension that needs to be no more than 5/8" and perhaps a bit smaller since the brass cylinder that fits there is a bit undersized).



I think I'll just leave my set up in place until my boring bar arrives. Until then, I can continue to mill other parts in the vise and I have several parts to turn on the lathe.

I thought about trying the 12mm mill instead of the 12mm drill, but all that I have are 4 flutes and I was afraid that they might want to walk.

Thanks for all the help!

 

[ttabbal]

Yeah, if you want an on size hole, a drill bit isn't the right tool. They always end up a bit over. Reamers and boring are the way to go for those. I prefer to bore, because I'm cheap and don't want to pay for a full set of reamers. I can make the boring head make whatever size hole I want. It's just slower.

Looks like you got a good clean cut without hurting yourself or your tools. That's a win.

 

[ChazzC]

It's odd that my google-fu missed finding this (and also the Inheritance Machine video). It's quite helpful.

I’ve found it interesting that Google’s search engine doesn’t do a great job of finding YT content (other than stuff that’s not that useful), particularly since they own YT.

YT’s search function also leaves a lot to be desired: in the YT app you can’t search within a provider’s videos (like you can on the web-based version), and good luck with [provider] Hemingway Knurling Tool.

Glad you came up with an approach that worked for you.

 

[rronald]

I’ve found it interesting that Google’s search engine doesn’t do a great job of finding YT content (other than stuff that’s not that useful), particularly since they own YT.

YT’s search function also leaves a lot to be desired: in the YT app you can’t search within a provider’s videos (like you can on the web-based version), and good luck with [provider] Hemingway Knurling Tool.

It's particularly egregious when you find part of a series and then you can't find the other parts. I found part 1 and 2 and 6, but it took me quite a while to locate part 3?

 

[GeneT45]

It's particularly egregious when you find part of a series and then you can't find the other parts. I found part 1 and 2 and 6, but it took me quite a while to locate part 3?

Usually the best way to find all the parts in a series is to go to the channel's home page and find their playlist for the series. Works for all but the busiest channels that just have too many videos to look through.

GsT

 

[ChazzC]

Usually the best way to find all the parts in a series is to go to the channel's home page and find their playlist for the series. Works for all but the busiest channels that just have too many videos to look through.

GsT

Yes, the good YTers will combine all parts into a playlist, and on the web you can search playlists.