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Finishing one piece doors cut on CNC1/12/18
We are cutting a lot of one piece doors on the cnc lately. Tooling sharp, look good after cut.
Finish schedule is sand 220g, sand 320 grit. Prime Clawlock, sand 320g, reprime Clawlock sand 320g. Color coat Resistant, scuff scotch brite, final color resistant.
No matter how well sanded and how well coated, there are micro pitting in the cut portion of the inset panel. The edges do not have this. You can only see them in certain light. Panel is smooth to touch just not up to snuff.
Interested in hearing others finish schedule and if anyone else has this problem.
Failed to mention, all coats are sprayed to appropriate mil thickness with CAT AAA.
What tool are you using to plow out the center panel area?
Using Onsrud insert door bits.
What type of MDF are you using? I used to have this issue with cheap MDF, switched to Medex and it hasnt been an issue since.
I'm not sure of the manufacture, but we are purchasing "door grade" mdf from Wurth Wood Group. Not cheap stuff.
What type of cutters are you using? In my experience carbide gave me a better cut than steel
He mentioned onsrud insert cutters, so carbide there. I use an Amana mini flycutter to plow out, and the carbide inserts dull pretty fast. I replace them about every other job. When dull, they tear and make extra work so we end up skim-coating the center panel with thinned out filler, which seems to mitigate the pinhole problem later.
Plum Creek MDF is pretty good for what you are doing. You'll probably have to try out a few different premium MDFs before you find one that comes up to your specs.
Appreciate your responses. "Grain fill" not really an option, kinda defeats the purpose of budget minded of one piece mdf door from labor stand point. Sounds like the consensus is brand of "door grade" mdf coupled with carbide cutters and making sure they are sharp. Will be trying other manufactures of mdf. Thanks
Well it also sounds like your mindset isn't really grasping the concept of budget doors either.
The little imperfections you speak of are because of the lower price point of the doors also. I know you want a beautiful product, but lower price does come with a limit to the quality of the product too.
Leo, I'd agree my mindset has a hard time grasping dumbing down my product. For 40 years we have built bespoke boutique cabinets. Have turned down numerous opportunities for less expensive cabinets and have had a hard time getting there.
The minor pitting just bothers me. Hard to see but I see it.
You're not telling me anything. I'm anal. And I guess you are too. Even when I'm doing price point woodworking I can't help myself to keep my high standard up. Costs me money so I try not to do that kind of work.
I feel for ya.
As Leo mentioned the Plum creek double refined mdf is necessary. There may be other brands of double refined.
How are you applying the sealer coat of primer? It should be done so that you can't see any of the mdf when you sand it.
We only use mdf for paint grade flat & raised panels . We use BIN as the mdf sealer. Its applied with a brush. 2 quick coats only on the cut part of the panel.
The BIN drys in 10-15 minutes. As you are going around the mdf it soaks it up. We set up all the panels and quickly brush around all the them. By the time we get back to the first one the BIN has started to set and the next brushed coat completely fills in the grain.
Our jobs are at the top end of the New England market. Porosity is not acceptable.
Your sanding & coating schedule is identical to ours. I don't think you are get enough primer on the sealer coat. Clawlock can be used in this way. It doesn't dry as quick as BIN. Obviously you could wait a few more minutes between the sealer coats.
Another thing you could try is a different primer. I use chemcraft plastiprimer for MDF. It fills in end grain and router cuts fantastically. Dries a good bit faster than clawlock
Appreciate all responses! Looks like we will have to try different seal coat and Plum Creek mdf.
I think you'll be surprised by the Plum Creek. I know I was. 1st coat of primer doesn't soak in. And the 1st coat on the uncut areas will be as much as you need. It really is great for panels, even flat ones.
Its come along way since the mid nineties when the industry standard was to use regular mdf and grain fill with sheet rock compound, bondo, gluesize, or you grandmother's secret recipe for mashed potatoes.
Double refined and the proper primer/sealer is the go.
Interesting forum, I gave up on cutting these doors a long time ago, because it seemed like so much labour to make them look good. It sounds like you guys are getting them figured out down to a science. I think I will get some of that mdf and give them another whirl. What diameter bit seems to be the best for cleaning out the majority of the panel?
Update: Purchased new bit set from Vortec, got Plum Creek high density MDF. Doubled up on Clawlock primer, other than that same finish schedule.
All of the above allows us to produce and finish our one piece doors to a very tolerable level quality wise. Too bad we have to buy the Plum Creek in whole units, supplier doesn't stock but can get at ok price per unit.
I thank everyone for their input in helping us solve this problem. Y'alls input and knowledge is valuable to us.
When it comes to sanding after that first coat of Clawlock, is anyone using any special profile sanding tools?
I thought about looking into the Festool Profile sander with the custom profile kit to custom make my own sanding profiles.
We use SurfPrep sander with 1/2" pads half on and half off (if that makes sense). It works well and can get in most contours.