Looking to upgrade spindle. What is the real world difference in the new 4 or 7hp units? I have 3 phase so could get the full benefit of the 7. The question is related to 3/4" plywood. Will the 7 cut in one pass compared to the 4?
I think it’s the Three B’s the Bigger the Better the Badder Yay!! 
I’m not aware of a precise answer but I remember this video from the 8.7hp release, it compares with the 4hp.
I used to do nearly single cut passes in an old non Avid machine I had in my shop with a 3HP spindle.
I was doing softer plywood with a 1/4" compression spiral bit. I’d aggressively cut in the climb direction, leave the parts slightly larger and then come back with a conventional pass and shave down the last little bit.
This made the edge quality really nice and accounted for any flex I introduced by cutting so hard. (I was doing 300+ inches per minute I believe in one pass)
This was right at the ragged edge of what the spindle could handle.
If I used a larger bit I’d have to back off speeds.
For that work, the 7 would have been perfect.
My recommendation is that if you want that kind of guaranteed performance with some headroom the 7 is the one to get.
You also need to think about hold down too, the more aggressive you cut the more hold down you need. In my case on that old machine I was doing a lot of sheet plastic and plywood. To cut more agressively in the sheet plastic I ended up not using my vacuum anymore and switched to ridgid fixture hold downs so I could go faster. Had I had a bigger spindle I could have gone even faster.
Thank you. I am going for the 7hp. I will have a 10hp Becker so my hold down should good. I’m not looking for extreme speed, just want 90% of what my 5x10 Pro can give me.
I have an s30 3hp and could run 3/4 ply at 600ipm 18000 rpm 2 passes with a 3/8 compression. Technically it was 3 but I would run a full sheet onion skin removed on the 3rd pass. The 7hp should be enough to run 1 pass easily enough. Depending on hold down and part size you should be in the 500-600ipm range 1 pass. The ideal is to climb cut with zero offset for the 1st pass and then conventional for the onion skin pass. It removes any flex and deviation that way…your parts will come out accurate. How many cfm is your becker?
This guy plywoods 