S-Splice Lams

Watsonjay · April 01, 2026, 09:11:14 PM

Alright, I decided to order a CNC Router. My hopes are to use it to make footed risers easier and better than a bandsaw and trying to sand to fit. Also going to try cutting s-splices in 1"x1.5" boards, glue together then cut lams on the bandsaw. Any tips and tricks from you guys that are experienced? Additionally, what glue would you use for the s-splice ea40?

Crooked Stic · April 01, 2026, 10:24:57 PM

You can use the CNC to make patterns for sanding jigs to use on a pattern sander

Kirkll · April 01, 2026, 10:25:04 PM

You could use white glue, urac, or EA-40 for the S-splice for veneers, but i'd stick with EA 40 for riser block footings. I'll be curious to see what type of CNC set up you get, and how user friendly it is. I've got a feeling you are going to get some good experience milling wood with high speed cutters.

Back when i first started building footed risers i set up a large router table and used 2" cutters with a flush cut bearing, and used patterns. Some seriously scary chit when one kicks back on you.

but i figured out how to safely use it.... But i had issued with tear out on some woods going against the grain at times that could have been mitigated by climb cutting. but.... climb cutting with a serious cutter should NEVER be done by hand.

I milled a lot of crown moldings years ago using high speed shapers, and learned to use a power feed for climb cutting, but it's still dicey as hell. Bottom line was i set up a pattern sander and use 36 grit on the edge sander for my footings, and gave up using the high speed cutters except for building new forms. They work great for that.

With a CNC set up i would imagine you could program the direction of cutter travel and eliminate a certain amount of tearout. But.... i have no CNC experience and can be of no help... Good luck on that adventure. I'll be curious how it works out for you.

But like Stic said, using that baby to make patterns for an edge sander pattern sander set up would be excellent. you can also make S scarf jigs and use a router or profile sander to cut those out..

Kirk

Watsonjay · April 01, 2026, 10:44:58 PM

I like the pattern idea. I hoping that with an 1/8" bit I can get clean cuts. I am working with software now preparing for when it comes in. You can set plunge depth for very small increments so hopefully it doesn't tear out. This is what I've got so far. I have this set to cut .028 deeper on each pass. Thanks for the glue info. I bought a thin kerf bandsaw blade to hopefully cut the lams pretty thin after splicing.

Kirkll · April 02, 2026, 10:25:36 AM

Looks good on paper.... I'll be curious to hear of your adventures after the chips start flying.... Should be fun....

What type of CNC did you purchase?

Watsonjay · April 02, 2026, 10:40:34 AM

As I am always on s budget, the cheapest one with good reviews and big enough to do a riser. Genmitsu 4040 Pro. If it works out im sure ill end up upgrading the spindle, but as this is my maiden voyage I didn't want to spend too much.

Watsonjay · April 02, 2026, 11:34:37 AM

Quote from: Kirkll on April 02, 2026, 10:25:36 AMLooks good on paper.... I'll be curious to hear of your adventures after the chips start flying.... Should be fun....

What type of CNC did you purchase?

If you go to 45 seconds in this video. Im going to do it like them and not go to the very edge and finish with bandsaw and sander
https://m.youtube.com/watch?v=Q9jfpJWM7Fs

They have some really cool processes with the pneumatics that I like too

Kirkll · April 02, 2026, 12:08:59 PM

Wow! Thats getting pretty high tech there. i watched the CNC set up videos, but didn't get into the drawing software to determine your actual shapes. I can imagine that takes time to learn too.

I admire your commitment, but i think i'll pass, and just stick with my vertical milling machine, and do the shaping free hand myself. This old dog would blow a gasket trying to learn a cad system and programing all this stuff.

Have fun with it!

BTW... once you get this down, i'd think about building some pattern sanding jigs for footings. You could easily sell these to bowyers in the future.

Watsonjay · April 02, 2026, 12:45:01 PM

Quote from: Kirkll on April 02, 2026, 12:08:59 PMWow! Thats getting pretty high tech there. i watched the CNC set up videos, but didn't get into the drawing software to determine your actual shapes. I can imagine that takes time to learn too.

I admire your commitment, but i think i'll pass, and just stick with my vertical milling machine, and do the shaping free hand myself. This old dog would blow a gasket trying to learn a cad system and programing all this stuff.

Have fun with it!

BTW... once you get this down, i'd think about building some pattern sanding jigs for footings. You could easily sell these to bowyers in the future.

I understand. I don't have a good pattern sander. So I would cut freehand and do a lot of fitting and never be happy. I have a bigger grizzly belt sander with an end table but it doesn't have a pattern guide and not a very good connection for leveling and staying put.

I was a computer tech and manager for about 30 years and that easel software is pretty easy to use. So didn't take long to get the basics figured out.

Kirkll · April 02, 2026, 01:04:25 PM

THat's cool...

I hope it works out well for you.

But...... a good pattern sander is very hard to beat for doing footings, and other things too.. I would be more than happy to take some detailed photos of how i mounted my pattern table solid to the motor end using 1/2" machined aluminum if you like.

There are a number of ways to set up a pattern guide too. i had a bearing machined slightly larger than my drum by a machinist. But it can be done just using a polished rub rail too. Some guys have their drum turned and flattened out, but i don't really think that is necessary just sanding 1 3/4- 2" stock. I have a 3/4" formica top i put over that machined aluminum so i can use the table for shaping belly ramps at 90 degrees. Actually i could probably do the limb pads on the sander too, but i prefer to do those on the milling machine while i'm boring the the location pins and threaded inserts.

Let me know if you ever get around to setting one up. Kirk

Watsonjay · April 02, 2026, 09:21:05 PM

Ill shoot you pics of the table and sander so you can see what im working with.

dbeaver · April 06, 2026, 09:06:53 AM

Youre going to have to sand the pieces of the footed riser coming off the cnc, same amount of room for error sanding for glue than off a bandsaw, if you pause and dig in what's the difference? The same amount of skill required in my opinion.

Enjoy your purchase but I don't think the end justifies the means. A cool piece of shop kit for sure, and way useful outside of bow building. Cnc is just a one time paid shop apprentice who cant sweep. I've seen a lot of the bow processes done on CNC and for as "exact" as you can make something its up to your skill to get the bow properly fitted.

Watsonjay · April 06, 2026, 10:42:22 AM

I don't think I will need to clean it up that much. I know it is taking some of the art out of it. I may end up using it more for making templates like kirk said but I really want to make the best bow possible.

Kirkll · April 06, 2026, 03:00:27 PM

The cool part about doing something on a CNC is repeatability. If you want all your bow risers looking exactly the same. That's a great way to go about it. i could think of a ton of other projects you could do with that machine around Christmas time.

i'll be curious how it pans out for you, and once you get it dialed in maybe think about building some footing jigs out of starboard material for a pattern sander. You might want to think about footing lines now too. that footing will need to be done before cutting out your riser shape on your new toy.

Watsonjay · April 06, 2026, 03:45:08 PM

Quote from: Kirkll on April 06, 2026, 03:00:27 PMThe cool part about doing something on a CNC is repeatability. If you want all your bow risers looking exactly the same. That's a great way to go about it. i could think of a ton of other projects you could do with that machine around Christmas time.

i'll be curious how it pans out for you, and once you get it dialed in maybe think about building some footing jigs out of starboard material for a pattern sander. You might want to think about footing lines now too. that footing will need to be done before cutting out your riser shape on your new toy.

Ya I was going to make 2 riser blanks of contrasting woods and cut the footers at the same time. Finish sand the joints, glue together contrasting woods with 1/8" of thin lams to make up for router bit, then run the second process of cutting out the riser from the glued blanks. I'll probably cut the shelf then too and chisel out sight window and shape grip. At least that is my plan right now....we will see

Watsonjay · April 09, 2026, 05:07:26 PM

Test run on 2x4. I have too close to the edge still risking tearout. Think I need to slow down travel too but looking good

Watsonjay · April 09, 2026, 06:09:17 PM

Came out pretty good. I need to raise the rear of the shelf, too thin at the back.

Kirkll · April 09, 2026, 08:29:44 PM

When you program the CNC, do you have options for the direction of travel?

I think you may find certain areas in the riser that are more prone to tear out due to the grain direction. If it's possible to slow the travel speed and climb cut those areas coming from a different direction, that will help out a lot..... there is a learning curve running high speed cutters, and different types of wood are going to mill differently too.

i'll be rooting for you!

Watsonjay · April 09, 2026, 09:49:44 PM

Quote from: Kirkll on April 09, 2026, 08:29:44 PMWhen you program the CNC, do you have options for the direction of travel?

I think you may find certain areas in the riser that are more prone to tear out due to the grain direction. If it's possible to slow the travel speed and climb cut those areas coming from a different direction, that will help out a lot..... there is a learning curve running high speed cutters, and different types of wood are going to mill differently too.

i'll be rooting for you!

Yes you can change the direction of travel. I just started a legit hardwood riser so we will see how it goes.

I know black widow uses cnc on their riser but I bet theirs cost at least a cool half million

Kirkll · April 10, 2026, 11:01:12 AM

Another heads up on your CNC millwork. I see you are cutting the shelf out too. While this isn't a bad thing, I would be very careful on your depth using the CNC having a sharp 90 degree transition from the shelf to the strike plate section is not a good thing. Those risers can crack at the belly side of the shelf or even the back side unless that transition has a slight radius. I would highly recommend cutting it an 1/8" shy of the finished depth cutting that shelf, then use your random orbital sander to finish shaping it. It will be much stronger getting rid of that sharp 90 degree cut line.

Food for thought.

Another thought might be using a cutter bit with a slight chamfer at the tip, or a tiny round over. But I don't know how that would effect your other machine work...