HELP: stair tread routing problem.

[Clarence Smith]

Hello

While doing my first practice cut on a spare 1" thick maple stair tread, I encountered 2 problems:

1) for some reason, the cut seems to be moving inwards an 1/8" or more as it nears the front of tread (seen in pics). Why is it doing this?

2) tear out at the edge - I didn't for the practice cut put a scrap piece against it - It has the 3/8" roundover. Will just putting the scrap on the front edge be enough even though it is rounded over?

3) would rpm's make a big difference when cutting maple? (on back of bit package: D mm <25 = 24000rpm) So, for this 3/4" bit - I have to go 24000rpm correct?


I am using a CMT 3/4" cutter #812.690.11 and a shooting bard type of arrangement.


Any other suggestions would be greatly appreciated - before I start on the 'good' pieces.


PS: you gotta love that Collins Tool Company stair tread template! Best $50 you can spend to get stair tread installation perfection! As you can see from the last pic - there is barely a 1/16" gap - it is so close to perfect, it takes a good 30-60secs of finesse just to get the tread in there

Thank you

[glenn bradley]

1) for some reason, the cut seems to be moving inwards an 1/8" or more as it nears the front of tread (seen in pics). Why is it doing this?

I am not clear on how you are dong this. We are talking about the non profiled edge, yes? Is there a reason to not just make this cut on the tablesaw? The only reason you cut path deviates is if your reference path deviates. How about a pic of your setup for making the cut?


2) tear out at the edge - I didn't for the practice cut put a scrap piece against it - It has the 3/8" roundover. Will just putting the scrap on the front edge be enough even though it is rounded over?

The roundover should be done last for this reason. You could make a profiled backer board for the best result. My second attempt at recovering from this error would be to score the exit edge with a marking knife or razor knife so that the fibers would stop at the score and not tearout past the desired edge.


3) would rpm's make a big difference when cutting maple? (on back of bit package: D mm <25 = 24000rpm) So, for this 3/4" bit - I have to go 24000rpm correct?

I would spin a 3/4" stright bit a little slower but, this will not help with your fouled reference path or the tearout.


Again a picture of your setup for making the cut would get you better responses ;-)

[Ethan Melad]

1) I would say either your wall's not square to the stringers or your tread's not crosscut square.
2) If that is the leading end of the tread as you rout the profile, I'd try taking more smaller passes instead of a deep cut.
3) Sounds right to me

What is going to happen at the wall? Will you have a skirt? If so, no real need to worry about the gaps, right?

[Jerry Miner]

the cut seems to be moving inwards an 1/8" or more

Not sure what this means. Are you getting "snipe"?---where the bit cuts a little deeper in the last couple of inches?

How are you guiding the bit? Bearing? fence in a router table? Edge guide? I would look at your guide system, making sure you are not using the already cut surface as a reference surface for the remainder of the cut.

2) tear out at the edge: Grain direction has a big effect on tear-out. Light cuts, sharp cutters, slow feed rate will help. "Climb-cutting" often produces better results but can be dangerous if you are not careful.

3) would rpm's make a big difference? For a 3/4" bit, I would keep the rpms at 24-30k.

If you are routing the front edge only, you are routing the long grain, not the end grain (which is more prone to tear-out)--so I don't think a back-up piece will do anything for you. I would rout the pieces while extra long and cut to finish length after routing. Make your cuts from front-to-back so the fibers are pushed into the supporting wood, not away from the wood into space.

[Jerry Miner]

OK. I read your post again and I think I understand this better:

the cut seems to be moving inwards an 1/8" or more

You're talking about the cross-cut (sawing operation) of the tread, right? What tool are you using? You might be getting blade deflection (in, say, a SCMS) or the blade could be heating up through the cut and warping slightly near the end, throwing the cut off line slightly. Try the cut in stages: a half-depth cut, then a full depth cut---see if that helps. Might reduce over-heating.

2) tear out at the edge: This is also from the cutting, not the routing operation? A shaped backer-block can help, but cutting front-to back should solve it.

[Clarence Smith]

My apologies Glenn. Was trying to keep it short.

I have included 2 pics of the basic set-up. Basically a shooting board/edge guide clamped to the tread. Board gets lined up to the marks I make from the tread template.

1) The side edge - the sides going against the wall on the left and right. ( NOT the front round over edge and NOT the back edge at the riser. ) Cant make the cut on table saw = I dont have one AND the walls/drywall aren't at all square. I cut as close to the marked line as I can with the jigsaw - the line up the shooting board, clamp it - then run the router right to left as in the new pics.

2) these treads I had custom made for me. But that tip on scoring with the marker knife is what I will do next along with painters tape too. Thanks great tip!

3) What would you run the bit at?

I have included a few pics. I don't have a lot of money right now for the 'perfect' set-up. I am making due with what I got.

Thanks

[Clarence Smith]

Hi Jerry

Your comment about 'snip' seems correct - the last few inches of the cut seems to be going deeper into the tread.

Using a guide/shooting board. No bearing. I made the shooting board, and ran the bit over it = leaving the bit and the board perfectly matched. So know I just line up the edges of the shooting board to the reference cut lines, clamp, and route.

2) Ok, tried to hog it on one big pass. Will try a couple of light passes next.

3) ok 24-30 then. Thanks

Just routing the side edges - these were premade for me.

Thx

[Clarence Smith]

Look at the first pic and the last pic. The 1st pic - the cut appears to be getting deeper into the tread near the end of the cut.

2) smaller pass it is then next time. I tried to hog it out in 1 pass.

No skirt, just acrylic sealant - then paint.

Thanks

[Clarence Smith]

OK. I read your post again and I think I understand this better:

the cut seems to be moving inwards an 1/8" or more

You're talking about the cross-cut (sawing operation) of the tread, right? What tool are you using? You might be getting blade deflection (in, say, a SCMS) or the blade could be heating up through the cut and warping slightly near the end, throwing the cut off line slightly. Try the cut in stages: a half-depth cut, then a full depth cut---see if that helps. Might reduce over-heating.

2) tear out at the edge: This is also from the cutting, not the routing operation? A shaped backer-block can help, but cutting front-to back should solve it.

Hi Jerry

Your comment about 'snip' seems correct - the last few inches of the cut seems to be going deeper into the tread.

Using a guide/shooting board. No bearing. I made the shooting board, and ran the bit over it = leaving the bit and the board perfectly matched. So know I just line up the edges of the shooting board to the reference cut lines, clamp, and route.

2) Ok, tried to hog it on one big pass. Will try a couple of light passes next.

3) ok 24-30 then. Thanks

Just routing the side edges - these were premade for me.

Thx

[Lee Schierer]

1) for some reason, the cut seems to be moving inwards an 1/8" or more as it nears the front of tread (seen in pics). Why is it doing this?

It appears that your guide is slipping as you make the cut. How is it being held to the work piece? If you are using quick grip type clamps, they don't hold well and will loosen due to vibration from the router. Use two C-clamps. One at each edge of the tread.



2) tear out at the edge - I didn't for the practice cut put a scrap piece against it - It has the 3/8" roundover. Will just putting the scrap on the front edge be enough even though it is rounded over?


Yes, use a scrap piece to prevent tear out, but it will need to be curved to match the bull nose or you will still get tear out. Or cut within 1/2" of the bull nose and then stop and cut from outside back into the tread in a climb cut. Climb cutting will not lift the edge grain. Do not try to make the entire cut as a climb cut, jut the last little bit near the edge.



3) would rpm's make a big difference when cutting maple? (on back of bit package: D mm <25 = 24000rpm) So, for this 3/4" bit - I have to go 24000rpm correct?


I would slow it down slightly

[Matt Day]

A few small things:

Maybe throw a couple more screws into the fence of your shooting board. That looks like MDF which can flex a bit. Can't hurt.

Make sure the shooting board is clamped down good and tight.

Put a straight edge on the fence of your shooting board to make sure it's straight.

[Pat Barry]

I'd agree with Lee's point that the guide is slipping. I assume you are clamping this to the stair tread. Vibration from the router and pressure from you trying to keep the router up against your shooting board are causing it to slip.
I agree with Glen's point to do the roundover last. If this isn't possible then you need a backer that matches the bullnose profile

[Clarence Smith]

It appears that your guide is slipping as you make the cut. How is it being held to the work piece? If you are using quick grip type clamps, they don't hold well and will loosen due to vibration from the router. Use two C-clamps. One at each edge of the tread.



Yes, use a scrap piece to prevent tear out, but it will need to be curved to match the bull nose or you will still get tear out. Or cut within 1/2" of the bull nose and then stop and cut from outside back into the tread in a climb cut. Climb cutting will not lift the edge grain. Do not try to make the entire cut as a climb cut, jut the last little bit near the edge.



I would slow it down slightly


Yes, I was using quick grip type clamps. THat would make sense now - as I push harder into the wood, vibes and pressure loosen it up. Thanks.

Climb cut for the last part, and like Glenn mentioned above - score the wood fibres too - and maybe some painters tape in there as well.


Thanks so much Lee

[Clarence Smith]

A few small things:

Maybe throw a couple more screws into the fence of your shooting board. That looks like MDF which can flex a bit. Can't hurt.

Make sure the shooting board is clamped down good and tight.

Put a straight edge on the fence of your shooting board to make sure it's straight.


Yes, its MDF. I will put in more screws and make sure it is clamped good with C-clamps as well.

I will check with a straight edge too.

Thanks Matt

[Clarence Smith]

I'd agree with Lee's point that the guide is slipping. I assume you are clamping this to the stair tread. Vibration from the router and pressure from you trying to keep the router up against your shooting board are causing it to slip.
I agree with Glen's point to do the roundover last. If this isn't possible then you need a backer that matches the bullnose profile


Thanks Pat.

Im going to get some better clamps.

Round over came with the treads - custom made.

I will make a backer and score the wood fibre too just in case.

Thanks Pat

[Sam Murdoch]

Lots of great advice for the problems you encountered with the set up you have and how to mitigate.

I can't add any useful advice but for what it's worth may I say that this is the perfect job for a track saw - along with the Collins Tool Company stair tread template this aspect of the job could not be simpler.