I’m making some speakers that need 2 sided machining on some of the parts. I’m not sure if I should try to flip the entire sheet, or cut out and then do the individual parts that need the second side done.
Never done 2 sided maching and my first test was off a little on the second side. I’m making some jigs right now that may help but wanted to reach out and see if anybody had advice that may save me some trial and error.
Thanks!!!
Hi Cameron,
Just make sure you have enough reference alignment dowels along the length of the sheet and you should be fine. The problem I see with long pieces is that just a few reference dowels in front will still allow the end to shift a little bit.
You don’t need jigs for it if you are doing it out of plywood; just do some 1/4" dowel holes that match in your spoilboard.
I second the advice from Corbin. I’ve done a lot of two sided sheet operations. My go to strategy is to use alignment pins or a sacrificial strip of wood attached to the table and machined to align with the long Y axis.
I had the best luck with having alignment pins on both sides of the sheet, e.g. Y- and Y+. I would use a lower left reference point for side 1 and lower right for side 2. Side 1 was handled with a G55 work coordinate system, and side 2 with G56. I could easily switch between the two, and this would account for any variance in sheet width (common with the material I was using).
As for flipping the entire sheet or just parts – I suppose that depends on what you are cutting. I did both. If one side was just dados or few through cuts, I would flip the whole sheet. Sometimes I had a sheet with many parts and only one or two of 'em needed two sided operations. In that case I might just flip over the individual parts, still using the strategy above.
Since I have a vacuum table, which approach was often dictated by which would best hold the work pieces.
Once you system is dialed in, you can very accurately do two sided operations quickly.
Thanks for the advice. I think it will be easier to flip the sheet in this case.
Novice question follow up…
If I mill holes for pins along the Y axis on both sides, I’d want to be able to use them in future jobs.
How can I align the pins in future jobs? Would I save the WCS in Centroid and be able to reuse it?
I’ve always had really good luck using (2) dowel pins at diagonally opposite corners of my stock and then I wait to do the individual part cut out untill i’m done with the second side. Also, the dowels are just for alignment, you will still want to secure your sheet using clamps, screws, composite nails, etc… Take some time to review your WCS origin relative to your dowel holes relative to your nested parts or your two sides wont line up… I find it’s best to program those holes along with your other parts after you nest your sheet.
Be sure to not reset your X/Y between flips. That is very important; the dowels provide the alignment on the flip. I recommend saving one WCS offset and touching off on your spoilboard and not the top of the sheet. That way you don’t have to reset the WCS at all, and you don’t have to waste an extra offset.
And yeah, for future jobs store the X/Y WCS offset at something, say G55 or G56, and lock it so you don’t ever overwrite it. Your alignment holes should be a relative distance from these, and you can repeatedly use that relative distance in other projects for consistency.
THANK YOU!
That makes sense. I really appreciate you taking the time!!