tenon % thickness VS. TWD thickness

Moderators: Jason Susnjara, Larry Epplin, Clint Buechlein, Scott G Vaal

Tim Massa
Senior Member
Posts: 185
Joined: Tue, Sep 19 2006, 7:30PM

tenon % thickness VS. TWD thickness

Postby Tim Massa » Wed, Sep 22 2010, 11:36AM

Can someone tell me if the material thickness change at the TWD affects the thickness of the tenon, being a % of material thickness?
If it does then I assume all the dimensions in the nest, as they relate to dado's and tenon dimensions, will be wrong since the TWD thickness change occurs down stream from this file information? Trying to get a handle on this and be able to make adjustments to my cabinet construction settings to get tighter fitting blind dado's. I don't see how the new blind dado Thermwood has developed will work with loose fitting joints.

Can some one please explain what is the logic using a % of material for the tenon thickness? I have always been puzzled by this.

Thanks
Tim

User avatar
Josh Rayburn
eCabinets Beta Tester
Posts: 1260
Joined: Wed, Jul 01 2009, 2:19PM
Company Name: Halls Edge Inc
Country: UNITED STATES
Location: Stamford, CT USA
Contact:

Re: tenon % thickness VS. TWD thickness

Postby Josh Rayburn » Wed, Sep 22 2010, 11:41AM

Tim,
The % of material thickness has nothing to do with the fit being tight or loose. What you need to tighten up your joints is a smaller value in the "fit clearance" field. This is the amount of space that is intentionally left in order for you to actually smack these suckers together.
Blind dado or barb dado, you would only need that one adjustment.
Hope this helps,
jnr
Josh Rayburn
Hall's Edge, Inc.
CNC Machining Service


Dell Precision T3400
Win7 Professional 64 Bit/Core2Duo E8400 3ghz/4 GB Ram/NVIDIA Quadro FX570

Tim Massa
Senior Member
Posts: 185
Joined: Tue, Sep 19 2006, 7:30PM

Re: tenon % thickness VS. TWD thickness

Postby Tim Massa » Wed, Sep 22 2010, 11:58AM

Hi Josh,

Thanks for responding. If I set my fit tolerance to 0" and still get loose joints then I need to start measuring parts and find out where the problem is. Is the dado to wide (perhaps a problem with the diameter of bit) or maybe my z plunge is to much (creating an undersized tenon)? Should the resulting parts measurements be compared to the nest dimensions or are the nests' dimension invalidated if I do a thickness change at the TWD?

Been battling loose and tight fitting joints for years and would like to get better Q.C. on my parts.

Thanks again,
Tim

User avatar
Josh Rayburn
eCabinets Beta Tester
Posts: 1260
Joined: Wed, Jul 01 2009, 2:19PM
Company Name: Halls Edge Inc
Country: UNITED STATES
Location: Stamford, CT USA
Contact:

Re: tenon % thickness VS. TWD thickness

Postby Josh Rayburn » Wed, Sep 22 2010, 12:05PM

Tim,
There's lots of variables.
When was the last time you surfaced your spoilboard?
Have you checked your tool diameters with a mic to see what they really are?
Do you have your tool diameters set up properly in tool setup?
In what condition are your inserts or how sharp is your surfacing bit / flycutter?
Do you measure your tools often enough including your surfacing tool every time you surface the wasteboards?
The list goes on but these are most important to check first.....
I actually don't know if the nest dimensions are still valid after an 'on the fly' material thickness change. I would assume so, but I'd love to hear TWD's input on that one.
Hope that helps,
jnr
Josh Rayburn
Hall's Edge, Inc.
CNC Machining Service


Dell Precision T3400
Win7 Professional 64 Bit/Core2Duo E8400 3ghz/4 GB Ram/NVIDIA Quadro FX570

Tim Massa
Senior Member
Posts: 185
Joined: Tue, Sep 19 2006, 7:30PM

Re: tenon % thickness VS. TWD thickness

Postby Tim Massa » Wed, Sep 22 2010, 12:15PM

Thanks Josh,

Yeah, your right about all the variables that can creep into the milling. This is what were examining right now in order to get more reliable results. I can measure my parts/cutting bits but I need to know what the resulting parts dimensions are supposed to be. Is it the nest dimensions or do we have to calculate it all out with the % of material thickness and the TWD thickness to get a correct/revised dimension.
Anyone able to explain the % of material thing for tenon thickness?

User avatar
Scott G Vaal
Thermwood Team
Posts: 1741
Joined: Tue, May 17 2005, 12:44PM
Company Name: Thermwood Corporation
Location: Thermwood Corp: Dale, Indiana
Contact:

Re: tenon % thickness VS. TWD thickness

Postby Scott G Vaal » Wed, Sep 22 2010, 12:22PM

Tim,

If you write CNC and change the thickness of the material, the nest in the eCabinet Systems will not match the values that are being cut at the machine (unless you were to change the same materials to the same thickness that you CNC'd them in the job itself). If you have a .75" thick material and a 55% Blind Dado Thickness % then the tenons will be .4125" thick. If you CNC and change the material thickness to .72", then the tenons will be .396" thick (55% of .72" thick material) in the TWD only. Not to mention that parts can grow/shrink due to the thickness change as well (example: a top between the left and right ends will have to get wider to make up for the left and right ends becoming thinner.) If you have fit clearance set to 0 and the fit is still too loose, It is more than likely a problem at the machine level or you have tooling set up wrong in the ShopBot Link.
Regards,

Scott Vaal
-Thermwood/eCabinet Systems-
Dell Precision / Xeon E3-1240 / 8GB RAM /NVIDIA Quadro K2000

Tim Massa
Senior Member
Posts: 185
Joined: Tue, Sep 19 2006, 7:30PM

Re: tenon % thickness VS. TWD thickness

Postby Tim Massa » Wed, Sep 22 2010, 2:12PM

Thanks Scott,

That clears up what I should be comparing what with.
Would this be any easier if the tenon thickness was a fixed value in the construction settings? What would be given up going from a % to a fixed value? I guess I'm still wondering what the benefits are with having the tenon thickness a % of material thickness. What's the philosophy regarding it?

I will look into my tooling and machine end as you recommend. After collecting a stack of notes it occurred to me that comparing these to the nest diagram may or may not be correct after TWD.
Getting loose or tight joints has been a bane from day one. Not just with the link. Anything that helps get this issue dialed in would be a big help.

Thanks again,
Tim

User avatar
Josh Rayburn
eCabinets Beta Tester
Posts: 1260
Joined: Wed, Jul 01 2009, 2:19PM
Company Name: Halls Edge Inc
Country: UNITED STATES
Location: Stamford, CT USA
Contact:

Re: tenon % thickness VS. TWD thickness

Postby Josh Rayburn » Wed, Sep 22 2010, 2:22PM

Tim,
I would also be interested to know the thought behind the % of material thickness. I don't dislike the way it is, I just never knew why it was made that way.
I would also find the idea of a fixed tenon thickness attractive, because it's that above all else which dictates what tool will ultimately be used to cut all those tenons / dadoes. From a 1/4" tool running at 300 ipm to the 3/8" tool running at 550 ipm makes a big difference in the time it takes to machine a large job.
jnr
Josh Rayburn
Hall's Edge, Inc.
CNC Machining Service


Dell Precision T3400
Win7 Professional 64 Bit/Core2Duo E8400 3ghz/4 GB Ram/NVIDIA Quadro FX570

Gary Campbell
Guru Member
Posts: 256
Joined: Sat, Apr 04 2009, 6:27PM
Company Name: ShopBot Tools Inc
Country: UNITED STATES
Location: Durham NC

Re: tenon % thickness VS. TWD thickness

Postby Gary Campbell » Wed, Sep 22 2010, 7:41PM

Tim, Josh...
I too wonder why a tenon thickness cant be set to a fixed number, but can understand why, using programmer logic, that it is that way. Lets say that you have 3/4 material and set a 1/2" (66%) tenon. Now change this cabinet to 12mm material.... tenons cant be cut. Programmers would now change to % to have a viable cabinet. Cabinet makers would want a warning as thier cabinet can no longer be cut bt the tools they designed it for. Yet another example why cabinetmakers and programmers cant think alike.

The eCabs tenon thickness and depth determine dado tooling. Period. Why one is fixed and one is a variable is beyond any cabinetmaker logic that I can muster. I have had more tooling errors after a material thickness adjustment than for any other cause. My latest irritation has been during the development of face frame seeds. Wishing to use bl dados on fronts to allow use of outsourced or pre-dadoed frames. Any cabinet with 3/4 (generic thickness) parts goes thru constant adjustments to keep the CNC cut tenons near the .485 target thickness to allow fitting into dadoed frames. Seems every unit is a different thickness. I would kill to just be able to set the tenon to .485
Gary Campbell
ShopBot Tools Production Support

ShopBot (eCabinets) Link Training & Support

User avatar
Jeremy Schiffer
eCabinets Beta Tester
Posts: 944
Joined: Tue, May 10 2005, 9:36PM
Location: Carnesville, GA
Contact:

Re: tenon % thickness VS. TWD thickness

Postby Jeremy Schiffer » Wed, Sep 22 2010, 9:28PM

It's been brought up before, but I'll chime in here, too. Count my vote for fixed dado thickness!

In response to the material change possibly creating a tenon thicker than the actual material, would that really happen often enough to warrant keeping the tenons as a percentage of material thickness? Not in my case. It would never happen. But if some folks use a 95% thickness, then maybe it would.

Seems like maybe an error trap in eCabs during the material-thickness change phase to check tenon thickness in relation to material thickness would be the answer: It would bring up a message informing you that the tenon is thicker than the material on X part of X cabinet.

Fixed thickness tenons would save a ton of headaches, not the least of which is being surprised by which bit the machine just picked up with which to cut a dado. We have to use 60% thickness dados on plywood cabinets and 50% dados on laminate cabinets just to make sure that the same bit is used to cut the dado.

Okay, that's enough of my rambling. I should be in bed, but (obviously) have itchy typing fingers. :joker:
http://www.corlanecabinetry.com

Intel Core i7-5820 3.3GHz, 16GB RAM, NVidia Quadro K2200 4GB, Windows 8.1 Pro 64 bit

Tim Massa
Senior Member
Posts: 185
Joined: Tue, Sep 19 2006, 7:30PM

Re: tenon % thickness VS. TWD thickness

Postby Tim Massa » Thu, Sep 23 2010, 9:12AM

With regard to warnings about the tenon being to big for the panel thickness idea, Isn't that what's happening with kd/rta placements and tenon insets already?
It would be consistent with the rest of the program.
Trying to audit my parts has been made more difficult with this % feature as it throws out the dimensions of the tenon in the nest if you do a material thickness change at the TWD. Now you have to remember what the % is and what the material thickness change was. Ditto for the dado's.
It seems questionable that this method is as helpful as it could be as it works against other features of the software (the nest dimensions) being able to quickly focus in on a fit tolerance issue and efficient tool pathing.
Put another way, what would you rather know when your faced with a cart of ill fitting parts, cut in house or from a Thermwood shop? The percentage of material thickness or a direct value that the tenon should be and the dado's are created from? Which is going to be easier for making adjustments? What sets up the next job for success?

User avatar
Josh Rayburn
eCabinets Beta Tester
Posts: 1260
Joined: Wed, Jul 01 2009, 2:19PM
Company Name: Halls Edge Inc
Country: UNITED STATES
Location: Stamford, CT USA
Contact:

Re: tenon % thickness VS. TWD thickness

Postby Josh Rayburn » Thu, Sep 23 2010, 10:40AM

Tim,
I agree, a fixed value would be one less variable in troubleshooting.
We run cabinet parts day in and day out - we're a CNC shop that cuts parts for other shops, period. No assembly, no finishing, etc. so it's my business to produce parts that fit and cabinets that work every day of the week.
I've found that there are just certain "maintenance" tasks that need to be done on a regular basis, like surfacing the spoilboard and wasteboards, measuring tools to account for wear (if they last long enough), cleaning the spindle and toolholders, and the list goes on. This takes almost all the variables away, and I usually have only a few things left to check if my fit isn't what it's supposed to be.
We check the fit on every job that leaves the shop.

I've found that there's only a few things that can go wrong after all the regular "maintenance" stuff has been done:
- fit clearance not correct
- depth clearance not sufficient
- actual tool diameter not correct (I don't always check the tools, but if I have a fit issue then I'm immediately suspicious)
- tool slipped or loose: check existing daylight, then measure tool again to see if the tool slipped or is loose causing inaccuracy
I've never really had to go past these points to get perfect parts.

It's worth noting that I've had to use different fit clearances based on the material I'm going to cut, for example, flake core needs more space than a veneer core material, and Fuma core (which I refuse to cut these days) would need a different fit clearance than a nice Columbia PureBond core, etc etc...

Also tool feed speeds come into play when deflection becomes present, so if you're cutting too quickly, you might get more or less than you're expecting on the width of a dado - this is based on a climb or conventional cut and the size of the tool of course.

Unfortunately, I think you're stuck doing the math to attempt to get it sorted out for now, but as mentioned, you'll still have to resurface everything and remeasure tools as a first step to eliminate the first plethora of variables.

Hope this helps,
jnr
Josh Rayburn
Hall's Edge, Inc.
CNC Machining Service


Dell Precision T3400
Win7 Professional 64 Bit/Core2Duo E8400 3ghz/4 GB Ram/NVIDIA Quadro FX570

Tim Massa
Senior Member
Posts: 185
Joined: Tue, Sep 19 2006, 7:30PM

Re: tenon % thickness VS. TWD thickness

Postby Tim Massa » Thu, Sep 23 2010, 12:35PM

Thanks Josh,

Yes it does. Good insights. I've just finished measuring my parts and recorded them on the report sheets. Also recorded maximum deviation within a part from what it was supposed to be. After a few of these reports getting labeled up I did a comparison of the reports and found that the parts dimensions were over and under sized consistently with respect to the parts location to the table. Checked the deer tracks on the table and measured their depths. Found the depths to be off by the same degree that the tenons were getting milled under and over sized. I now know how important the spoil board can be when it comes to tenon thickness.

I'll attack the dado widths next and bear your advice in mind. The % thing was getting on my nerves in doing all of this. Had to question it, as it seemed to make this task more difficult than necessary.

Thanks for your practical advice. I will have to implement a maintenance and check list and will utilize what you've mentioned. Much appreciated.

Tim

Kenneth Rychlik
Senior Member
Posts: 161
Joined: Thu, May 04 2006, 11:09AM
Location: Southwest Houston
Contact:

Re: tenon % thickness VS. TWD thickness

Postby Kenneth Rychlik » Fri, Sep 24 2010, 6:02PM

Tim,

A few more things if you are running a 'bot

Are you zeroing to the spoil board or the top of the material? Top of material will give more eratic results.

Is your zero plate correct in your settings thickness as compared to checking it with a caliper?

Both of these could mess you up too.

Kenneth

User avatar
Kerry Fullington
Wizard Member
Posts: 4566
Joined: Mon, May 09 2005, 7:33PM
Company Name: ProSource of Amarillo
Country: UNITED STATES
Location: Amarillo, TX

Re: tenon % thickness VS. TWD thickness

Postby Kerry Fullington » Wed, Oct 06 2010, 7:50PM

Could you not calculate the percentage to give you your consistent tenon.

Say you want a 3/8" tenon thickness in material that measures 25/32

Divide your desired tenon thickness .375" by your actual material thickness divided by 100 which is .007812
and your tenon thickness setting would be 48.00307% of your material thickness.

You could do this for any material and have consistent tenon thickness.


Return to “eCabinet Systems Software”

Who is online

Users browsing this forum: No registered users and 3 guests