Looking for temporary use of a zero clearance throat plate for 3D modeling

[LCHIEN]

D_meister, are you saying the air currents affect the ability of the printed part to stay flat while cooling?
THat you need an enclosure around the printer for precision parts to prevent distortion while cooling after printing?

[jlmeredith]

d_meister - Thanks for the feedback and suggestions! I will be sure to take this info into account as I am working forward. Right now I am in the throws of replacing my shims, but once that is completed I can do a full test cut.

The edge lift you are experiencing can be addressed by using a brim and then shaving that off after with a trimmer (or as you indicated, having an enclosure, which is always the best way to address warping).

LCHIEN - Your question is correct. PLA prints at a much lower temp than many other FDM materials, and is prone to warping if the ambient temp where the part is being printed is not at least 30-35C/86-95F. Drafts do play an important role, but ambient temp is more important than drafts. As the part cools, if the ambient temp is too low, the part will cool too fast, especially in situations where there are long threads of filament laid out in lines, and curling will occur. I do think that the latest version with the grids on the bottom will be less prone to warping as there will be filament laid down at right angles to the long edges and this will help the part stay flat.

As I noted above though, I simple brim will fix this in almost all situations, as well as making sure to wipe the build plate with IPA before every print. Depending on the build plate material, adding some glue can help as well. I print with a textured PEI plate and never have adhesion issues, but I also have 10 years of experience with FDM printing and have owned more than 40 printers in that time. Currently my print farm consists of eight Bambu P1S printers and two X1 Carbon printers that all have full enclosures and I rarely if ever have issues with lifting, but I understand the pain.

d_meister Regarding the dado blade, I am not sure I understand completely. Can you provide a photo for reference? Are you saying when the blade is fully lowered, the plate touches the dado blade teeth? Are the dado blades a standard 10" set?

[LCHIEN]

d_meister Regarding the dado blade, I am not sure I understand completely. Can you provide a photo for reference? Are you saying when the blade is fully lowered, the plate touches the dado blade teeth? Are the dado blades a standard 10" set? [/QUOTE]

The recommended stack dado is 6" for the BT3x00s, there are actually some fit issues with the 8" stack dados.
I have never seen a full 10" dado for any saws.

[d_meister]

The warping is actually taking place during the print as the extremities are cooling, probably due to uneven build plate heating. But it is an inexpensive printer I've fought this battle with this printer extensively, and I usually keep a layer of 3M Blue painter's tape on the beds, especially the PETG printer. The PLA printer application of blue tape had exceeded it's useful life and messed up the print initially, so I just removed it and printed direct on the spring steel textured plate
The bed/build plate is suspended in space, and the thermister seems to be in the center, so uneven heating and cooling is probable without an enclosure. I've shielded on 3 sides on difficult prints in the past with carboard with good results. The PETG printer is in somewhat of an alcove, so has less issues, although a window nearby affects the front of the build plate more from the thermal currents. As Jamie notes, an enclosure is the solution.

The blade that made contact is a Diablo 10" 24 tooth ripping blade. What's remarkable about it is that there are few enough teeth so the blade may be clocked to a position where no teeth can make contact.

The ZCTP is actually providing more clearance in it's deformed condition, but the tooth is actually higher than the inside surface. This picture doesn't show it well, but the thickness of the top varies because of the warping during build. The lift is slight enough that the hot end irons the surface during the process. There is also post-print warping. It looks worse than it is in the photo. That triangular "cloud" is some kind of software artifact and has no difference in texture or surface level.
Incidentally, I went through the arbor carrier system, cleaning and lubing, a week ago, so I'm confident it goes all the way to the basement. Hasn't operated so smoothly in years!

There's not much clearance, there. Maybe 3/32"? And that's below the ZCTP mounting surface.

[d_meister]

Thanks for the tip, Dave. It's on auto cooling with the speed from 10 to 100%. I think you're right about turning the fan off, since there are no long bridges in the build. A lot of tricks in this game.
Stringing was bad for me all of a sudden a few prints ago on PETG, but it was picking up moisture. Had some nice days and opened the windows. I blasted it in the microwave a few times and then dispensed it from a plastic bag until I ran it out and changed rolls. That one is feeding from inside of a plastic bag, for sure. A good video testing moisture in filaments is Here. My PLA was just breaking spontaneously in the section between the roll and print head overnight when it wasn't running, so I researched it quite a bit.
I've been printing the newest ZCTP from Jamie, and it was doing well. Late in the print the corners furthest away have picked up and curled. New layer of Blue Tape had it doing better than before, but there's just no substitute for environment control with big prints. I'm printing the larger section of the ZCTP and it just fits on the platen diagonally. I stopped the print. I was running it because I modded the deck thickness above the blade, filament is cheap, I had a dust collection fitting on the other printer, and every day is a school day Once the prints start the the first few layers, I go and make sawdust and the printers can just run.
It's time to make an enclosure with all the clear plexi I've been hoarding.

[jlmeredith]

I have my new shims installed and I will be reassembling things today to test. Will update when this is completed.

[jlmeredith]

I have the attention of a knowledgeable group of people so asking for a side quest - do any of you recognize this as something on the saw?

The part has very regular wear marks so I think it is something that is supposed to be on the saw? It was wedged at the top of the screw that moves the saw head up and down.




ad

[LCHIEN]

I mean offhand it resembles the wide arbor spacer... which is very precisely 1/2 inch wide with a 5/8" ID hole.

But I know from your pictures you already have one in the right place. And I don't know why it would have 6 presumably dust circles on its side.

[jlmeredith]

I am thinking that it maybe a part to another tool that somehow got wedged up inside the saw. As you indicated, the two metal arbor spacers are in place. This is plastic, so not sure that it actually goes on the saw.

[jlmeredith]

Did not investigate the mystery plastic ring much.

Shims installed and first official test cut completed!

[LCHIEN]

Looks like you have very little clearance. Maybe near Zero.
Smells like success!

Is that a one-piece or two-piece solution?

You can clearly see its an ATB blade.

[jlmeredith]

This is the the two part design. I will be working on changing that to use a mortise/tenon design I think. Video post coming up next!

[jlmeredith]

Video showing lower clearance from the ZCTP when the blade is fully lowered.

Video showing the first cut through of the ZCTP on the saw after shims were replaced.

This is the full height of the blade from the throat plate which I think is where I should be.


Additional side shot from the left side of the blade.



I will need to make some design adjustments to address where the throat plate is not hollowed out enough toward the front of the plate.


No noticeable rubbing or marks from the arbor washer in the fully up position, so I think the cut outs are working as expected.


Will need to make some adjustments for the screw heads to fully recess. Additionally, I need to make some adjustments to the interface of the base of the plate and the screw down points as screwing things down bends up the ends. This may also be due to the top portion not being completely solid.

[jlmeredith]

LCHIEN d_meister - Let me know what you guys think!

[LCHIEN]

I think its great!.

I have one suggestion:

Seems like the joint requires some means of fixing in place (glue?). Perhaps, Instead of the dovetail joint:

Maybe fill in these sections solid. Then put two axial holes in the sections running lengthwise to the plate... intersecting the split. Holes of say 1/8" or 3/16" diameter about 5/8" deep into each half.

The you can use some inexpensive, widely available metal roll (spring tension) pins of 1/8" or 3/16" x 1 inch long into the split for alignment.


Maybe a printed mortise and tenon is neater, needing no external parts. But the roll pins can make all 3 axis alignment near perfect and the spring force will keep them together under low forces to pull them apart. But this is an special form of mortise and tenon.
Just a thought.
Amazon lists a pack of 16 roll pins for $9. https://www.amazon.com/Hard-Find-Fas.../dp/B00OP62KVC

25 pack 1/8" x 1 for $8.42 https://www.amazon.com/Prime-Line-9187812-Slotted-Spring-25-Pack/dp/B07DS5N6VJ

I'm sure local ACE or Lowes or HD has them as well individually or Graingers or any industrial supply or fastener companies will have them in bulk (100+ qty) if needed. Graingers has 3/16" x 1 $22.29 to 24.59 for steel or stainless steel per 100. 1/8" x 1 steel for $7.55 for 100

Lowes says they have them 1/8" x 1" 2-pack for $1.28

I just want to know when I can place an order for mine... :-)

[jlmeredith]

This is a great idea!

The current joint was strictly for the purposes of prototyping (and it would work if glued I think), but now that I feel pretty good with where this has landed, I will look at better options for the joint.

I like the idea of the roll pins as it only requires a hole on each side in a solid body segment. I just ordered a 25 pack and will start adjusting the design to include their use. I will update once I have a working sample!

[d_meister]

Looks great!
Maybe just glue the joint. There will not be a need for disassembly, so just slap it topside down on a true flat surface with glue and hold it in the aligned position until set. Definitely work on the screw support area to prevent deformation. If there's enough thickness there, maybe make a counterbore to set in a pan head screw head. A flat head screw will always deform relatively soft plastics by trying to force a cone through it.
I like the mechanical engineering approach Loring suggests. I look forward to your progress with that, Jamie.

[LCHIEN]

Looks great!
Maybe just glue the joint. There will not be a need for disassembly, so just slap it topside down on a true flat surface with glue and hold it in the aligned position until set. Definitely work on the screw support area to prevent deformation. If there's enough thickness there, maybe make a counterbore to set in a pan head screw head. A flat head screw will always deform relatively soft plastics by trying to force a cone through it.
I like the mechanical engineering approach Loring suggests. I look forward to your progress with that, Jamie.

Good point about the counterbore hole... plenty of meat there and a flat heat tends to be hard on plastics. A pan head machine screw is easy enough to get.

I question a glue approach... getting the right amount of glue into a tight precision joint like the part will have is iffy, nor sure what glue to use. A solvent glue or super glue risks setting up too quickly while you are trying to get the parts perfectly vertically aligned. The tension joint of the roll pins is good for near perfect alignment in all axes and there's no force on it when the plate is bolted in with four screws. Its not coming apart in normal use or handling.

Another idea I had was a variation on the pocket hole joint. A angled (typically 15 degrees) threaded hole could be made where I suggested putting the roll pins. A self-tapping pocket hole screw with a head could be used (maybe iffy if a dado head is used) or a long skinny set screw could be used... although the ability to put 3D print a threaded hole is probably not possible. But its really to give some tensile strength to the joint that it probably doesn't need. The roll pins give it plenty of shear strength and alignment.