Protecting your bed BEFORE it cracks, and alternatives to glue stick (Page 2 of 3)

i have read a lot about what to use to adhere projects to beds and what height to set the clearance of the nozzle at but im curious as to how large of a surface area are everyones prints ( mine are pretty large, about half the size of the bed ) and what everyone sets their first layer height at because i'm thinking that the first layer height would have to be close to the clearance of the nozzle. i've tried several adhesives and settled on glue sticks but not with 100% success. i set my clearance at .28mm with a feeler gauge and have modified the bed to be able to adjust all 4 corners and my first layer height is .35mm. this printer is a continually learning process and i'm always up for suggestions. i'm using for production of parts for a $570 million invention that i'm working on until i can have the parts made by injection molding ( if anyone would like to see it they can go to dudad.net ). i look forward to hearing what ideas are out there to prevent warping for larger prints. thanks

Warping is caused by uneven cooling. The outside of the part cools before the inside. The solution is one keep the entire part at a higher temp and cool slow as in setting the bed at a higher temp like I do which still does not work with large parts.

The other solution is forced cooling bu having a secondary fan that blows down directly on the part as it is printed. this cause all the layers to cool evenly and usually eliminates warping. I am in the process of designing a low profile fan duct and mount that will cool the active print area below the head. However I may wait till I covert to an E3D first.

For every glue stick or can of hair spray there seems to be yet another option to get the parts to stick to the platform.  I'm a fan of the blue painters tape simply because it works - it's easy to find when one roll is gone (will be a looooong time though) and I use 210 on the extruder / 90 on the platform.  I've not printed as many parts I'm sure as some of the other members but after all that I've done (and this represents a lot of variety in shapes, sizes, widths and heights - guess what, the painters tape just keeps on working so I'm not sure why some others seem to have so many issues but this combination works reliably for me.

If I bought another machine tomorrow, would I expect the same numbers and the blue tape to work equally well - absolutely not!  I would probably start there, but I would not be surprised if either or both of the temperatures required something slightly different - mostly because these are "production line machines" and they come to you with all of the possible process variables that XYZ can come up with for a company that is basically producing at relatively low volumes.  They probably aren't building or buying batch quantities much beyond 200 or possibly 500 to 1000 of anything simply because they don't produce that many total units and they don't want their money sitting in the warehouse in raw materials.  They want it in the bank and will use it carefully to stay slightly ahead of the production line needs.  If that's the case, then most of their suppliers are also working in small batches and there's where the variations come in.  Whether it's components on the pc-board or extruder tips, the possibilities for variations all contribute to what you get as the "shippable nominal" that passes the inspector that says - yes, it's within this range - it's shipping!  In spite of all that, it still works relatively well and more than anything else it seems to me the ability to get something satisfactory out of your machine is simply a balance of your expectations along with how well you've "learned" some of the critical things about your machine.  Pay attention, take notes, try new things but most of all, don't imagine that your machine should work precisely like mine or 50 others - it will be close but that word is relative for all of us!  Tweaking and tuning is required as are our adjustments in our expectations from time to time.  If this machine retailed for 5,000 instead of 500 my expectations would be significantly different as would everyone else that bought one!  Given the price and the output from it, I still believe it's a remarkable value - as is the blue painters tape!  Thanks.

ok cool makes sense. sorry it took so long to reply, i drive a truck during the week so i stop here n there to check on my laptop. i usually have my first layer at .35 and my clearance at .28, seems to work ok and i've been using extra strength glue stick and have tried kapton tape but not painters tape yet so ill give it a shot but i am printing a part that pretty much covers half of the bed. some times i get a little warpage on the edges. well gotta crash for a few hrs but if you've got any other advice ill check in a few hrs and thanks a ton for all the help so far

You really need some sort of method to cool the entire layer as it is printed that keeping the entire print for the most part at bed temp. You need to figure out a way to add a fan to your extruder so it blows down on the print as it is printed.

Warping is caused by uneven cooling. On a large print the outside cools faster so based on thermal expansion the cooler area will be pushed away from the hotter area so it makes the edges and corners curl up since they are connected and cannot expand outward as well like the force is trying to make them do. To defeat that you either have to keep the entire print warm which the bed helps but does not do well enough as the print gets thicker.

So we go with the opposite approach and cool the entire layer as it is printed thus keeping the print at a uniform temp. You might think this is counter productive to bonding to a previous layer. It does not however cause any real difference in the bond. As the hot layer lays down it is hot enough to still melt into and bond to the previous layer even if the layer is cool.

I ordered these from Amazon for $18.45 (free shipping)
10 Pack: 8" x 8" x 2mil 3DXTech Polyimide Tape Sheets Kapton for 3D Printer Platforms. Polyimide Tape offers an excellent print surface for 3D Printer Platforms. The polyimide tape is 2mil thick (0.05mm) with Silicone Adhesive and a PET release liner. This tape provides a smooth heat-resistant surface that easily removes once you have finished your print. Polyimide Tape offers excellent electrical insulation, high temperature resistance, and high voltage resistance. Suitable for use on Makerbot Replicator, Ultimaker, Prinrbot, Reprap, Mendel, Prusa, Up! Printers, Solidoodle as well as most other 3D Printers.

I will update this post after trying these out.....

Thanks for the write up. I read this before I started my first print and now on my 5th print (like 8 hours in) I see I chipped the glass. I waited for the printer to say it was down cooling and removed my item and now I have a nice little canyon in my glass. I'll order a new glass bed from xyz when their shopping cart starts working again and start investigating where I can get some thin glass to put on top.

These have saved all sticking problems and adhesion problems.....They are hard to put on if you try to stick them on dry....if you clean the glass on your bed...spritz a little water on the bed...the Kapton tape squares slide nicely around and needed no trimming. I them heated the bed (by submitting a job) and slowly worked the air bubbles and water out with a credit card. After it got to 90C all the water was gone...I tested several prints and, once cooled, there is nothing to releasing them and revealing the nice glassy finish. I'd give this item a thumbs up for the DaVinci 1.0..

The local "expert" here has one and says AquaNet hairspray works much better than the glue stick. The prints stick good but once they cool off they pop right off without the chance of breaking the glass.

Used the uhu glue stick and then wetted it, smoothing it out better on the bed.
Still early experimental. I think the few major sticking events were due to poor glue spreading.

Does an extra layer of bed glass get in the way? The initial extruded positioning is close.

So I just wanted to share that after getting my chip in my glass I started using masking tape (frogtape brand masking tape to be exact) and although I'm now the proud owner of two spare printing beds I haven't bothered to change it out yet.  The masking tape has been working wonders for me.  I figure I'll keep using the masking tape until I have this thing mastered and then venture to change the bed and still use masking tape after that.

The tape works great. I put down 4 strips, use an xacto knife to get the edges clean and then print. I tend to replace the two middle strips after every or every other print and the two outside strips every few prints.  Even though I have a nice chip in my glass the tape goes over smooth and I still manage to get a smooth service to print off of.