MDF blow outs

[NCKIII]

Hi

I install pre primed mdf casing and base trim and can't seem to avoid chipping when the finish nails go into the material. I've tried Hitachi, Porter Cable and Dewalt 18 gauge guns. Can I hit the edges of my nail racks before I put them in the gun or do something to the drivers etc? Any information would help on this. It irritates me that the surface chips out most of the time. What I mean by chips out is that I don't get a clean round hole, I get a hole plus another piece of the mdf or paint that falls of and it's about 3 times the diameter of the nail head.

Thanks,
Nick

[James Eggert]

I never had good luck using 18g nailers for large trim. I suggest trying a 16g gun. You still have to have the painter fill anyway, so a slightly larger "clean" hole would be easier to fill and sand.

[tjbnwi]

I just got the Grex Green Buddy 18 ga (they have a cheeper one, it does not work as well). The driver leaves a clean hole in MDF.

Tom

[NCKIII]

Jim,

Do you have any trouble splitting the small part of 356 casing? I sould see using it on base but not the 356 inside portion that seats against the door jamb.

[NCKIII]

Thanks Tom, I'll look for it. Have not seen that brand in any tool stores around here.

[tjbnwi]

I bought my Grex 23 ga. pinner from a local Woodcraft which has since closed. After going through 3 18 ga. guns in a few years, I decided it was time to do some research. The Grex was the best I could find.

I ordered mine online, wasn't real thrilled with the dealers service, so I won't recommend them. If you have a local Woodcraft, check there.

Make sure it is the GB you are looking at, it's about $200.00.

Here is a video showing the hole it leaves;

http://www.youtube.com/watch?v=5E9KMIPOdFM

Tom

[joseph]

wait - the way i read this he is having trouble with mdf . i have never had it do what he has happening with any of my guns .sounds more like a batch of junk mdf . I get a mushroom at times that needs to be sanded but never a pop out .I need the author to try some different material /supplier and report back

[James Eggert]

NCK
I should have been specific, because I agree that using an 18g on the smaller portion of the casing trim is the way to go. But i have not had any problems with lumps and blow-outs? I do not use 18g on base at all because I want it to stay on!

Maybe it is the gun you're using?

[Alaskan Son]

In my experience, the MDF can vary quite a bit. Sometimes the primer coat tends to chip easily, and the lightweight MDF behaves differently than standard MDF. And I agree the larger hole will probably finish better anyway.

Edit: On a side note, I always use a 16 gauge gun for MDF. I think using the smaller gauge gun may be the reason some people have problems. Because MDF needs to be filled and sanded anyway, the larger nail holes are actually better anyway, and make for a much better connection to the substrate. No real benefit to using the smaller gun except at some of the thinner profile areas or places that are that are trim to trim only (such as the casing to jamb connection or at miters).

[MarkMc]

... is that I don't get a clean round hole, I get a hole plus another piece of the mdf or paint that falls of and it's about 3 times the diameter of the nail head.

Round hole? What is the head geometry of the brads you're using? Are they round? When you switched guns did you also switch brad brands? Driver [piston] slop, gun angle, driver wear/deformation, material can all affect the results.