Using 80/20

[99sport]

My cuts, and the factory cuts, are out of square by about 0.2 degrees and this makes for structures, when they are several feet long, that are noticeably out of square. Have others run into this issue? What kind of saw are you using and how square are your cuts? Am I being unrealistic expecting my structures to be square to less than a 32nd of an inch over 3 or 4 feet?

I'm using end connectors (https://8020.net/3381.html).

When I first built the below shower enclosure, which is about 2' x 3', it was out of square by about 3/16" (difference between the two diagonals). I flipped half of the tubes over, and it is now perfectly square, but the bottom is no longer flat. I will fix that by bolting the 4 corners down to the van.



After investigating, I cut all the tubes with the same face pointing up. My saw blade was not quite square to the fence, and I made all of the tubes as parallelograms (/===/). Below is a picture showing that the cut is not square. Note that I would not accept a cut that is as bad as shown, but after adjusting my saw I am still seeing about half this angular error.



Since all my tubes were parallelograms in both axes / directions, flipping half of them over does exactly what you would expect, fixes the out of square, but throws the tubes out of plane (ie base is no longer flat).

I have a $100 Craftsman miter saw I bought about 20 years ago, but it has not been used heavily, which has a nonferrous blade. I adjusted the saw and, judging by my square, one axis is square. The other axis was slightly out of square, and I adjusted it, but it seems the saw bed is not flat as the blade is now square on one side, but slightly out of square on the other side of the blade.

After investigating and adjusting, I am making all cuts on the side of the saw where the bed is square to the blade, and I am flipping the tubes to make trapezoids (/==\) instead of parallelograms (/==/). One direction now makes "perfectly" square cuts, but I am still not quite getting square cuts in the other axis / direction - I think the cuts are out about .125" over 3 feet, which works out to an angular error of about 0.2 degrees, but I do not think there is any way I am going to get my saw dialed in better than that. I also checked the squareness of the factory cuts, and they have about the same error - in other words my setup gives cuts that are as square as the edges from the factory.

Your thoughts?

 

[brownvan]

My cuts, and the factory cuts, are out of square by about 0.2 degrees ..

If the factory cuts on your order are out-of-square I would bring this up with 80/20 and ask them resolve it. They have excellent customer service and have always resolved issues for me on past orders. I've had pieces with scratches in the anodize, damaged corners and a few other issues and they have always resolved it by replacing the pieces for me. I do know they've been really swamped with business for the past few months so it may take a long time to resolve.
I can't offer much advice in adjusting your miter saw to get double-90's. I know some of the issue might be due to cutting technique as I have experienced this before when cutting my own extrusion with a carbide wood blade. Blade might be deflecting under full cut - maybe rough cut and then take off .010"-.020" increments and see if that improves? Perhaps there's a way to make a temporary rake/guide out of wood and VHB tape to orient your extrusion to the blade more precisely? Or rotate the extrusion 90/180/270 after cut and lightly skim the ends? I know this will throw off your lengths so maybe just fine tune the ends with a belt sander (or vertical belt sander if you own one).

 

[99sport]

My 8020 is from McMaster-Carr. I don't know if they cut stock lengths in house, but I doubt it as the faces are very smooth and there is a small chamfer on all 4 edges. I have checked more extrusions, and my freshly adjusted saw is definitely closer to 90 than the as delivered extrusions.

Making a small final pass is a good idea. Thanks

Close up of the factory cut (1st picture) and my cut (second picture) - again my cuts are now MORE accurate than the factory cut:

 

[GeorgeRa]

Practically all my cuts were done by 8020 folks, all straight. See the galley frame.

 

[99sport]

Practically all my cuts were done by 8020 folks, all straight. See the galley frame. View attachment 167922

Did you check the diagonals for square? How close were the measurements?

 

[GeorgeRa]

Squareness of cuts was well demonstrated by good fit of the CNCed countertop with holes to the galley’s posts threaded center holes. Except a few threads for end connectors all my parts were machined at the factory, it is rather doubtful to attain the same level of accuracy, cleanliness of cuts, or squareness with home tools. I had no dimensional issues with 8020 assembly. My decision to use factory machining services was one the best one for my conversion.

I had one problem with one shipping but 8020 folks sent me new parts.

Accurate Aluminum Extrusion Machining | 80/20 T-Slot Solutions

View 80/20's Standard Machining Services - A wide range of extruded aluminum precision machining for cuts, drills, & bores.

8020.net

 

[99sport]

Squareness of cuts was well demonstrated by good fit of the CNCed countertop with holes to the galley’s posts threaded center holes. Except a few threads for end connectors all my parts were machined at the factory, it is rather doubtful to attain the same level of accuracy, cleanliness of cuts, or squareness with home tools. I had no dimensional issues with 8020 assembly. My decision to use factory machining services was one the best one for my conversion.

I had one problem with one shipping but 8020 folks sent me new parts.

Accurate Aluminum Extrusion Machining | 80/20 T-Slot Solutions

View 80/20's Standard Machining Services - A wide range of extruded aluminum precision machining for cuts, drills, & bores.

8020.net

How much clearance did the CNC countertop holes have? In other words, if you used a .250" screw, was the clearance hole .256, .280, or .375? Did you have to compress along the diagonal to start the screws?

Pre saw adjustment, a .375 clearance hole on a .250 thread in a 22" x 36" assembly would line up easily without having to squeeze the diagonal. I'm thinking I should be getting more like 1/32" to 1/16" difference on the diagonals for a structure that size, which would allow .280 clearance hole on a .250 fastener for your countertop example. However, .280 clearance on a quarter inch screw is in the realm of macinened part tolerances. I guess what I am getting at is are my expectations for tolerance on theese assemblies unreasonable? I'm curious how much tolerance others are getting on their 8020 assemblies.

 

[Dave D]

My cuts, and the factory cuts, are out of square by about 0.2 degrees and this makes for structures, when they are several feet long, that are noticeably out of square.

I have a $100 Craftsman miter saw I bought about 20 years ago, but it has not been used heavily, which has a nonferrous blade. I adjusted the saw and, judging by my square, one axis is square. The other axis was slightly out of square, and I adjusted it, but it seems the saw bed is not flat as the blade is now square on one side, but slightly out of square on the other side of the blade.

After investigating and adjusting, I am making all cuts on the side of the saw where the bed is square to the blade, and I am flipping the tubes to make trapezoids (/==\) instead of parallelograms (/==/). One direction now makes "perfectly" square cuts, but I am still not quite getting square cuts in the other axis / direction - I think the cuts are out about .125" over 3 feet, which works out to an angular error of about 0.2 degrees, but I do not think there is any way I am going to get my saw dialed in better than that. I also checked the squareness of the factory cuts, and they have about the same error - in other words my setup gives cuts that are as square as the edges from the factory.

Your thoughts?

I recommend getting a better miter saw. My Bosch 10” compound miter saw can be adjusted to square and will stay in that position for 8020 cuts with a good blade. It’s a $500 saw but it paid for itself on my first crown molding project. I understand your frustration on 1/32” as have metal working tools where 1/1000” makes a difference. Over the years I’ve come to the conclusion that my time is too valuable to work with crummy tools.
Note- Ive ordered pre-cut parts from 8020 and been pleased with their accuracy.

Here’s my little CNC mill sitting atop an 8020 stand I built for it.

 

[Graphite Dave]

All my 80/20 cuts for two conversions were done in my shop with a wood chop saw and proper blade for aluminum. Did not notice any issue with cut ends not being square. Also made most of the connectors with the chop saw.

 

[jdubbayew]

An update--I haven't built anything yet, working on other things. But I did order parts and everything seems like it should work just fine. I also found a better solution for the mounting plate for series 10 installations, no adapter plate needed. It has the right spacings--0.5" from front face to hole, right over the T-slot. Would just need to drill out holes a bit larger for the 1/4-20 screws needed for series 10 hardware. I'll build a prototype soon just to confirm everything works before placing my bigger order. Will post results.

https://www.parts4cabinets.com/prod...mbly-type-mounts-with-8-pan-head-wood-screws?
View attachment 163837

Just confirming these do in fact work perfectly with the 1/2 soft-close hinges on 10 series frames.

I was also able to get my southco latches to grab the 10 series slot to lock the cabinets in place and eliminate the need for a separate catch.

 

[GeorgeRa]

How much clearance did the CNC countertop holes have? In other words, if you used a .250" screw, was the clearance hole .256, .280, or .375? Did you have to compress along the diagonal to start the screws?

Pre saw adjustment, a .375 clearance hole on a .250 thread in a 22" x 36" assembly would line up easily without having to squeeze the diagonal. I'm thinking I should be getting more like 1/32" to 1/16" difference on the diagonals for a structure that size, which would allow .280 clearance hole on a .250 fastener for your countertop example. However, .280 clearance on a quarter inch screw is in the realm of macinened part tolerances. I guess what I am getting at is are my expectations for tolerance on theese assemblies unreasonable? I'm curious how much tolerance others are getting on their 8020 assemblies.

The standalone galley was perfectly square to the ¼” diameter holes in the countertop. Once mounted to the van’s floor I placed a strap on diagonal to regain alignment. Ultimately, the countertop holes were drilled with 3/8” drill to accommodate for thermal expansion difference between aluminum and HDPE.

 

[goinoregon]

Just confirming these do in fact work perfectly with the 1/2 soft-close hinges on 10 series frames.

I was also able to get my southco latches to grab the 10 series slot to lock the cabinets in place and eliminate the need for a separate catch.

could you post a pic or two??
thx

 

[RVCuisineScene]

I used 80/20 extensively in my build, great stuff, I've been a carpenter for 40+ years, get a new chop box with a new carbide blade with lots of teeth, a cheap blade will heat up and distort its shape when used for cutting 80/20. Everything I received from 80/20 had square cuts.

 

[goinoregon]

I used anchor fasteners in the overhead cabinets for rigidity in order to maximize the load on the very strong lower mount and to move upper load to the roof ribs mounts from tensile towards shear loadsView attachment 148938View attachment 148939. There is only one place where anchors are visible.

hi george,
what is the extrusion p/n that you can put the sliding doors in? and what is the thickness of the sliding doors?

 

[GeorgeRa]

I used 80/20 2218-48 upper tracks https://8020.net/2210-48.html and 80/20 2220-48 lower tracks https://8020.net/2220-48.html.

Panels are ¼” HDPE with interweaved on upper and lower edge Teflon coated fishing line resulting with no vibration.

Using 80/20

I found a picture of using a plate for corner assembly in the sofa bed, note inside angle. I could not find one with flat head bolts but it doesn't make a difference for strength. This corner assembly is likely stronger than $20 corner cube. George.

sprinter-source.com

hi george,
what is the extrusion p/n that you can put the sliding doors in? and what is the thickness of the sliding doors?

 

[Dotar]

When I first used 8020 a few years ago I used a band saw and just figured that a bit of misalignment was normal. With the passing of years and bigger projects, the school of hard knocks revealed small errors are magnified to unsatisfactory results. Now I use a Festool Kapex saw and always check for square on each setup and always use stops to insure repeatable cuts. I apply wax to the blade each cut and never force the blade. Best results come by letting the blade stop after the cut before retracting the blade. Check X and Y with a machinist square on test cuts before production cuts.
Before

After

 

[99sport]

Thanks all who replied to my posts. With some slight tweaks I am now getting excellent results:

- It is imperative to have a good support for long extrusions - a dedicated infeed and outfeed setup would be invaluable, but I am cutting everything outside as I don't want my shop (with 4 spare engines in it) filled up with aluminum shavings. Be very diligent about making sure the long extrusions are exactly parallel to the saw bed.
- I adjusted my saw with a small framing square. One axis has a detent and it was already basically perfect. The other axis has an adjustable stop, so I adjusted that and it is now square as well.
- I am making the final cut only taking half the width of the blade kerf. This does seem to make a difference.

Still using the same $100 saw with the same $50 blade I am now getting cuts that are square to about .005" over 24" in one plane and about .010" to .015" over 24 inches in the other plane. After implementing the above tweaks, this works out to a perpendicularity of less than 0.04 degrees. This is about an order of magnitude better than the 8020 extrusions as delivered from McMaster Carr which are around .2 to .4 degrees perpendicularity with the factory cuts. While still not perfect, the difference on my diagonals is now about 1/16" on a 2' x 2' frame.

As others have suggested, I do have a top of the line Dewalt miter saw, which I bought to frame a hip roof where every single cut is a compound miter and every piece is a different length - it is an absolute pleasure to use and is highly recommended, but for 8020 where every cut is 90/90 I think it is overkill and I did not want to fill an expensive saw with metal shavings. Based on my latest results, I do think you can get good results with a good quality, but inexpensive saw and a good blade.

While I think my cut quality is quite good, it is definitely not as good as Dotar's picture. Dotar, what kind of blade are you using to get that surface finish? And what is the speed (RPM) of your saw?

 

[jdubbayew]

could you post a pic or two??
thx

 

[goinoregon]

Thanks all who replied to my posts. With some slight tweaks I am now getting excellent results:

- It is imperative to have a good support for long extrusions - a dedicated infeed and outfeed setup would be invaluable, but I am cutting everything outside as I don't want my shop (with 4 spare engines in it) filled up with aluminum shavings. Be very diligent about making sure the long extrusions are exactly parallel to the saw bed.
- I adjusted my saw with a small framing square. One axis has a detent and it was already basically perfect. The other axis has an adjustable stop, so I adjusted that and it is now square as well.
- I am making the final cut only taking half the width of the blade kerf. This does seem to make a difference.

Still using the same $100 saw with the same $50 blade I am now getting cuts that are square to about .005" over 24" in one plane and about .010" to .015" over 24 inches in the other plane. After implementing the above tweaks, this works out to a perpendicularity of less than 0.04 degrees. This is about an order of magnitude better than the 8020 extrusions as delivered from McMaster Carr which are around .2 to .4 degrees perpendicularity with the factory cuts. While still not perfect, the difference on my diagonals is now about 1/16" on a 2' x 2' frame.

As others have suggested, I do have a top of the line Dewalt miter saw, which I bought to frame a hip roof where every single cut is a compound miter and every piece is a different length - it is an absolute pleasure to use and is highly recommended, but for 8020 where every cut is 90/90 I think it is overkill and I did not want to fill an expensive saw with metal shavings. Based on my latest results, I do think you can get good results with a good quality, but inexpensive saw and a good blade.

While I think my cut quality is quite good, it is definitely not as good as Dotar's picture. Dotar, what kind of blade are you using to get that surface finish? And what is the speed (RPM) of your saw?

View attachment 168227

View attachment 168226

i increased the dust control on my miter saw recently. taped, bolted some heavy duty vinyl around the rear to guide dust into the standard chute, then added a rubber gasket to attach my shop vac. this combo does an incredible job of catching saw dust, and would highly recommend. i added the same gasket to table saw, and then tried to fully enclose bottom of saw, and most of the misc holes. with vac going it now gathers much of the saw dust. sorry for poor pic quality

 

[goinoregon]

I used 80/20 2218-48 upper tracks https://8020.net/2210-48.html and 80/20 2220-48 lower tracks https://8020.net/2220-48.html.

Panels are ¼” HDPE with interweaved on upper and lower edge Teflon coated fishing line resulting with no vibration.

Using 80/20

I found a picture of using a plate for corner assembly in the sofa bed, note inside angle. I could not find one with flat head bolts but it doesn't make a difference for strength. This corner assembly is likely stronger than $20 corner cube. George.

sprinter-source.com

thanks for the p/n's ! i apologize, but i don't understand the following statement: "with interweaved on upper and lower edge Teflon coated fishing line" ?
thx
greg