Raised Panel MDF finishing

[Steven Hans]

Hello all,
I made some raised panels out of mdf. They come out really nice. I use a shellac based primer and sand and reprime and get that glass smooth finish. Initially though, the cut is quite rough and bumpy. Sanding fixes that, but I was wondering if I could set up my router table again with the panel raising bit and run those panels through to get a nice smooth finish? Anyone did something like this before? I have that Freud quatro bit. If this would work, it would be a great short cut for sure!

Thanks for any thoughts.

[Todd Burch]

My experience with priming MDF is that the first coat of anything you put on it is rough. However, after sanding, it's smooth (and smoother) from there on out.

I don't understand your sequence of events. Are you priming and then wanting to re-route? Or, are you suggesting a different approach (from what - you didn't say) for raising the panel?

Your topic is "finishing" and this is the finishing forum... should it have been "profile sanding" or "profile routing" instead? I'm confused.

You are getting a bumpy profile with your panel raising bit. How much are you currently taking off for the last pass now? How many passes now? Do you get a bumpy profile with solid wood? How big are your panels compared to your router table top? What size router? How bumpy is the profile? I have a Hitachi MV12 mounted in a CMT table, and no, my raised profiles are not perfect, but they are pretty good. My bumps in my profiles are operator error (dust or chips under the panel, jerky movements, changing hands as I feed the panel, inconsistent feed speeds). The slower you go, and the less you take off, the better the results.

Todd

[Steven Hans]

I apologize for not being clear. The sequence of events is as follows: route the profile, prime the profile, sand the profile, and reprime the profile. I was wondering if I could just set up the router table and replace "sand the profile" with finish route the profile to get a smooth surface. This is "finishing". I just wondered if I could use the the router to replace the sanding to get smooth surface after priming. My cuts are perfect and smooth using mdf. But the surface of cut mdf needs to be primed and sanded. As soon as you put that primer on, the surface is rough and bumpy. I don't need tips on routing, and that wasn't my intention. Just was wondering if anyone was successful with running there mdf job back through the router after priming to get a smoother surface.

[Mel Fulks]

I have never heard of that, can't say no one has tried it .Sounds like you are at a point where what is needed is a quick ,easy sanding with a sponge type sanding block .Do not over do it. You want to remove just the roughness.

[Ole Anderson]

Why not just try it on a sample cut and report back? Might just be the best thing since sliced bread, or the worst, never know till you try. I presume you would leave the router set for the same depth of cut as the panels were originally routed for. So all you are doing is slicing off the raised grain, any finish that soaked in would still be there.

[Todd Burch]

I apologize for not being clear. The sequence of events is as follows: route the profile, prime the profile, sand the profile, and reprime the profile. I was wondering if I could just set up the router table and replace "sand the profile" with finish route the profile to get a smooth surface. This is "finishing". I just wondered if I could use the the router to replace the sanding to get smooth surface after priming. My cuts are perfect and smooth using mdf. But the surface of cut mdf needs to be primed and sanded. As soon as you put that primer on, the surface is rough and bumpy. I don't need tips on routing, and that wasn't my intention. Just was wondering if anyone was successful with running there mdf job back through the router after priming to get a smoother surface.

Sure you could do that.

I don't know how much you pay for MDF primer, but I pay a lot. I would not route it off after I applied it.

Since your raising cuts are perfect and smooth, then I suspect the "rough and bumpy" you are feeling is the feeling that is expected to occur after priming router-cut MDF edges. So, you could do your test of route, sand, prime, route, and then you will have wasted a coat of a primer, and when you prime again, you will feel the "rough and bumpy" again, putting yourself in an endless loop of pain. (a bit of exaggeration here)

I've never heard of anyone doing this sequence before.

[Steven Hans]

I am gonna try it and report back. I have 12 panels. I will do one to see.

[Steven Hans]

I couldn't get it to work. The finish came clean off. Perhaps if I left my router bit in the router and didn't mess with the adjustment it might work? However, I promptly dissassemble, clean, put away my bits after I am finished with my cuts. It is best to stick with a sanding sponge. Worth a try I guess.

[John Lanciani]

I use a sand-o-flex in a drill to sand my raised panel profiles after priming MDF panels. Quick and easy way to get them smooth and ready for top coating.



http://ecx.images-amazon.com/images/I/51tBx4qlHzL._SL500_AA300_.jpg

[Steven Hans]

Good tip! I need to try that