Bi-directional Single-Pass Tenon Cuts?

[Jeremy Schiffer]

The addition of the ability to have the preliminary outline cuts as climb, with final pass conventional, was a real lifesaver and cut quality improvement. Would it be possible to implement the same strategy for the Single-Pass Tenon Cuts? As it is, they are done in a Conventional cut direction, and when the part is then outlined, there is always a ridge (between the lock dado tenons) caused by deflection (of what? That is another rabbit hole...)

I'm attaching a picture to show what I'm talking about - this causes a gap in the assembled pieces because the Single-Pass Tenon cut is not actually straight, but arcs inward and the back outward as the machine ramps up and then back down during the cut.

If the Single Pass Tenon cut could do a climb first so as to deflect away from the part, then conventional to clean it up, that would fix this issue and make me a very happy camper. Thanks!

[Neville Bastian]

So its just not me.

[Clint Buechlein]

The addition of the ability to have the preliminary outline cuts as climb, with final pass conventional, was a real lifesaver and cut quality improvement. Would it be possible to implement the same strategy for the Single-Pass Tenon Cuts? As it is, they are done in a Conventional cut direction, and when the part is then outlined, there is always a ridge (between the lock dado tenons) caused by deflection (of what? That is another rabbit hole...)

I'm attaching a picture to show what I'm talking about - this causes a gap in the assembled pieces because the Single-Pass Tenon cut is not actually straight, but arcs inward and the back outward as the machine ramps up and then back down during the cut.

If the Single Pass Tenon cut could do a climb first so as to deflect away from the part, then conventional to clean it up, that would fix this issue and make me a very happy camper. Thanks!

IMG_20201103_145305.jpg

Jeremy,

Can you post a picture of the whole edge being cut on single pass so I can see the entry location as well? Do you see this on both your 45 and 41? And some questions about the tool that is doing the work: Manufacturer, part number, spindle speed, and feed speed?

-Clint-

[Jeremy Schiffer]

Hey Clint,

By "the whole edge being cut on a single pass", are you referring to the Single-Pass Tenon? If so, the beginning of it looks just like the end that is shown in the picture, except it has the arc ramp-in. The entire length of the Single Pass Tenon cut is an arc, due to the machine's acceleration and deceleration - therefore the ridge shown in my picture is largest at the center of the cut. Our outline cuts are set to Climb cuts down to the skin thickness, then the final outline thru-cut is Conventional. If I'm misunderstanding you, let me know and I'll be happy to send whatever pictures you may need.

We do see this issue on both the 45 and the 41. It is worse on the 41 though, likely just because of the age of the machine (looser bearings, etc.). But both machines do show this issue in both X and Y direction of cut.

The bit we use for both the tenon cut and the outline cut is Southeast Tool SMDUD551, which is equivalent to the Vortex 3185XP.
The Single Pass Tenons are run at 18,000 RPM, 315 IPM.
The Outline cuts are at 18,000 RPM, 630 IPM.

Thanks for looking at this!

[Clint Buechlein]

Hey Clint,

By "the whole edge being cut on a single pass", are you referring to the Single-Pass Tenon? If so, the beginning of it looks just like the end that is shown in the picture, except it has the arc ramp-in. The entire length of the Single Pass Tenon cut is an arc, due to the machine's acceleration and deceleration - therefore the ridge shown in my picture is largest at the center of the cut. Our outline cuts are set to Climb cuts down to the skin thickness, then the final outline thru-cut is Conventional. If I'm misunderstanding you, let me know and I'll be happy to send whatever pictures you may need.

We do see this issue on both the 45 and the 41. It is worse on the 41 though, likely just because of the age of the machine (looser bearings, etc.). But both machines do show this issue in both X and Y direction of cut.

The bit we use for both the tenon cut and the outline cut is Southeast Tool SMDUD551, which is equivalent to the Vortex 3185XP.
The Single Pass Tenons are run at 18,000 RPM, 315 IPM.
The Outline cuts are at 18,000 RPM, 630 IPM.

Thanks for looking at this!

Jeremy,

Can you either post an export or send it to cabinets@thermwood.com, as well as the CNC code used for the part?

I could see it possibly being deflection on the 41, not so much on the 45, unless the tool is hanging out of the collet a good bit, or the collet is severely worn. The tool should be in the collet as much as it can for stability. At minimum you want to look for 1 1/2 times the diameter of the shank.

Reading back on my response I wasn't clear about what I wanted a picture of, but nonetheless. What I was wanting to look for is how much of a ridge there is at the entry motion of the arc. If it is tool deflection, you should see the ridge getting wider as it gets to final depth. As the load increases, the deflection increases so the ridge should have some taper to it.

My initial though is there is a mismatch in tool diameter. If you turn off Single Pass Tenon cuts do you still see the ridge?

-Clint-

[Jeremy Schiffer]

It couldn't be a tool diameter issue, since the same tool is used for the tenon cut and the outline cut (same tool number as well).

I would imagine removing the Single Pass Tenon Cut would help (though not solve) the issue simply because the machine never gets up to full speed, as it is making a small pocket for each tenon, and therefore won't flex as much. BUT... that Single Pass Tenon is a HUGE timesaver.

The bit is in the collet as far as it can be without flutes going into the collet. (forgot to mention in my last post that it is a 3/8" dia. bit)

We have done a lot of testing here to try to narrow it down, frustratingly to little avail. But here's what we've been able to figure out:

It is somewhat more pronounced when the cut is in the X direction (both machines) - why? The machine itself isn't as rigid in that axis, because the Y axis can allow a tiny amount of movement in the Y axis as the cutting force increases - at least, moreso than the X axis can allow movement for a Y-axis cut.

Bits flex a tiny amount, collets flex a tiny amount, and when combined with a small amount of machine flex, I think it all adds up to the rather large amount of flex seen in my picture. That's all we can figure, especially since both machines exhibit the same traits (albeit the 45 to a lesser degree).

The reason we like the outline being climb-then-conventional is for these same reasons. At least that way, the initial flex (be it machine, bit, collet, whatever) is away from the part, and the climb cut then has nearly no cutting force, and you end up with perfectly straight edges.

So naturally, we figure if we could have the single-pass tenon also have the option to first do a climb, then conventional cut, it would solve the problem.

I'm sending the email with the files you requested.

If you need more details let me know. If a phone call would be more efficient, we can do that too.

Thanks!

[Jeremy Schiffer]

My email got bounced back as spam.

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Shall I rename them to .txt files and post here?

[Clint Buechlein]

You can upload them here http://info.thermwood.com/thermwood-file-upload-page.

-Clint-

[Jeremy Schiffer]

Just did, gracias

[Clint Buechlein]

Jeremy,

Got the files. As a note just to make sure we are on the same page, when a single pass tenon cut is done, there is a downward arc that is in the same location as where the outline cut will be made outside and within the tenon cut. So there is not really side load on the tool unless the bottom is dull. This should be helping to alleviate any tool flex.

Can you recut this part, but instead change your Direction to Conventional rather than the two passes with different cut directions? I'd be interested to see what results you have.

Also, when you measure the part, which one has the correct measurement? Within the tenon or outside the tenon? Or neither?

-Clint-

[Jeremy Schiffer]

Hi Clint, got a few more pics (randomly pulled this part from a job currently being cut)

At the moment, I can't recut any parts because the machines are busy, but I will when they become available. But, based on experience (before the climb/conventional option was available) the part will not have any straight edges, they will all be concave as a result of the deflection towards the part. And there will be a ridge at the bottom of the part as a result of the final/skin pass having no cutting force. Hopefully that makes sense.

Also, when you measure the part, which one has the correct measurement? Within the tenon or outside the tenon? Or neither?

Hard to tell, because the material thickness change during TWD creation causes all the parts to be oddball sizes. If I measure the part from the bottom, it measures consistently. Measuring from the top, obviously the part tends to get narrower as you move toward the center of the cut.

Check out the pics here - I'm sure you probably don't need them, but just in case we're on different pages:

[Jeremy Schiffer]

Here's a Y direction cut

[Clint Buechlein]

Jeremy,

Thank you for the additional pictures. We currently have a demo going on, but if it ends at a reasonable time, I'm going to cut the part from your original picture and see if I get the same results. I'll post back as soon as I get on a machine.

-Clint-

[Clint Buechlein]

Also, for sake of asking, what is your dado depth in eCabinets? Does it vary or stay pretty consistent?

-Clint-

[Jeremy Schiffer]

Here's a shot of our settings - 1,000 words and all that