Planer Molder question

[nrp0450]

I have a Belsaw planer/molder (5 hp) and have a question about using it. I'm doing a shiplap subfloor with this machine and am looking at set up options. I would like to plane the boards and do the shiplap without changing knives all the time or having to stack and sticker. We will be doing this over the course of a few weeks, milling logs for the boards, planing them to 3/4", shiplaping the edge, and screwing the boards in place. The head on the planer/molder has 3 slots for gibs and knives. When you run molding you're only supposed to have one knife in and you use counterweights in the other two slots. I'm wondering if I could leave two planer knives in and put my shiplap knife and enough gibs and counterweights in the third slot to balance out the weight. I did some googling and couldn't find anyone saying this should be avoided or that it's OK.

I don't know if I'm explaining this well. Here's a visual. Imagine this is the surface of the head rolled out flat.

/-planer knife-/-planer knife-/-planer knife-/-planer knife-/-planer knife-/

/-planer knife-/-planer knife-/-planer knife-/-planer knife-/-planer knife-/

/-counter weight-/-counter weight-/-counter weight-/-**molding knife**-/

Would this work?

[Larry]

I haven't done that, but I have done something similar.

/small space/planer knife/small space/counter weight/

/small space/planer knife/small space/counter weight/

/small space/planer knife/small space/molding knife/

Actually I was using the planer knife to cut back relief for casing and the molding knife or the right was doing the front side.

Didn't used to be a big deal or expense cutting planer knives short to do back reliefs.  I would think that would be less expensive than extra counter weights.

Really if I was contemplating what you are attempting, I would pick up another Belsaw.  Seems like they go fairly cheap anymore.

[nrp0450]

I would love to have another Belsaw so I could just leave one as a dedicated planer and use the other for molding and other stuff. But I don't think I could fit another one in my shop. They're huge.

I don't think the planer knives I have leave enough space to fit a molding knife next to them on the head like you did, Larry. I guess I could see if I could get some 10" planer knives.

I'm pretty sure I have enough counter weights to get the head balanced. Though I'm not sure how to know when it's balanced. I could weigh the parts but the angular momentum of the molder knife (that sticks out a good bit further than planer knives) would change things. How do you know if it's balanced?

And would two planer knives (not evenly spaced around the head) still do the job?

[Larry]

You just cut down the planer knives to whatever length you need.

If my memory is right planer knives are 1/8" thick and molding knives are either 1/4" or 5/16".  It would be a pretty good trick to get the head balanced with your scheme.

Gibs might be another problem.  Again from memory I think there are three with a short one centered in the head.