Troubleshooting Sanding Swirl Marks on Five-Piece Doors

      A door manufacturing shop gets advice on methods to eliminate swirl marks without laborious hand sanding. February 11, 2010

Question
We manufacture five piece doors and I am looking for a solution/set-up for my sanding. Right now we finish our doors in this process. Timesaver 3 head sander 150g on first head, 180g on second head, then 220g on third head (combination head). Next we run it through our profile sander (Loewer) at 180g. The last step is the orbital (timesaver) first head is orbital at 150g and last head is brush.

I can get rid of cross grain but then I am left with swirls. To not get the swirls I seem to be leaving the cross grain. I can't find a happy medium between the two. I am trying different pressure, different paper and I have even tried reversing which machines come first but Iím not sure which way is the best for me to go. Any advice is appreciated.

Forum Responses
(Cabinetmaking Forum)
From contributor G:
About two minutes hard block hand sanding with 180 will do it. Do you finish them in-house?



From contributor W:
I would think since your last orbital grit was 150, you should hand sand with at least 150 or maybe even 120 to completely remove the swirl marks.


From contributor L:
180 on a Dynabrade running at the proper RPM leaves barely noticeable scratches. You might try skipping all the sanding machinery and tighten up your joinery so as not to require so much sanding. I use a PC random orbit with a top of the line abrasive. Start with 120, finish with 180. No scratches. It goes pretty quick due to quality of abrasive.


From contributor C:
Tightening up joinery is good advice for actually saving time in the long run. I run all parts through a wide belt (and hand detail tight areas) before assembly. Then just clean up the joints with orbital. I sand from 100 to 120 to 150 (stop here if stained) then to 180 (for a clear only or dye in the clear finish). The way I understand it is you don't want to polish raw wood, especially if you intend to leave it stain ready.


From contributor R:
Why has no one suggested dropping on down to 180 or 220 on the R/O timesaver?


From contributor W:
I agree with dropping to 220 but there is still going to be some crossgrain scratch removal and then following up with some hand sanding to remove slight swirls created by random orbit. Hand sanding one grit courser then the last grit random orbited works like a charm for me - flawless finish. I generally finish random at 220 and sand by hand with 150.


From contributor L:
I have never seen a swirl mark with my simple PC RO. I think how hard you press and how sharp your paper has a lot to do with it.


From contributor R:
Iíve seen them before, but not in a long time, maybe is my eyesight.


From contributor U:
What are you using for swirl pattern cut, diameter of cut, and what is the orbit stroke? We have a Dynabrade that is tight and it is impossible to get the swirls out.


From contributor L:
Not sure of all the technical details. It might be your first Dynabrade grit is too aggressive or you are pressing too hard since your abrasive planing the joinery. This may leave marks too deep for progressive grades to remove. I've also noticed the RPMís too low will leave more swirl marks. Maybe a manufactureís sanding rep would know more.


From the original questioner:
The problem is that we produce 100 plus doors a day and we have to eliminate any and all hand sanding prior to shipping the doors. I am going to try changing to a higher grit paper and I have called the sales rep in but Iím waiting for him to show, which sometimes takes a while so I need to try to come up with a solution in the meantime.


From contributor G:
"Last step is the orbital (timesaver) first head is orbital at 150g and last head is brush." This 150 orbital is where you are picking up swirls. Contributor R and others have suggested using finer grit on the final sanding and I agree. You might also consider mesh graded sandpaper. It sounds as though you a door manufacturer and are supplying unfinished doors. If your customers are staining the doors, the finisher would likely want to (should) hand sand them anyway. If the doors are being clearcoated - no problem, except maybe 320 would be too fine in that case, resulting in potential adhesion problems. Some people routinely hand sand outsourced doors anyway. You could ask your customers and find out.


From contributor U:
You left out a whole bunch of critical information about your widebelt. What are the diameters and hardness of your drums? You could eliminate 99% of your work if you have a properly setup widebelt sander with the third head having a chevron belt and pad combination. Until you have seen the quality that can give you with almost no cross grain scratches, you will not believe me.

From contributor G:
As contributor U pointed out, the answer starts with a good widebelt finish. If you need to use 150g on the orbital head sander to remove crossgrain scratches caused by the widebelt you need to look at getting a better finish from your widebelt. The grit sequence on your widebelt should do the job if the sander is properly set up and can hold very tight tolerances. Have you ever tried a finer grit on the orbital? The brand of paper can even make a difference.


From the original questioner:
I am going to be trying finer grit on the orbital and I was told by the sales rep to look for 3m micron paper. They say that paper leaves the least noticeable swirl marks.


From contributor T:
I'm curious - enlighten me a little more on the chevron belt and pad if you would. Is this something that can be added to any widebelt? I've never been happy with the finish on my timesaver.


From contributor U:
A chevron belt is a second belt that runs inside the machine at a different RPM as the sanding belt. It will give you the best of both a contact drum (short cross grain scratch) and a pad (very shallow cross grain scratches) to the point where the crossgrain is not visible. It is amazing. It is not something you can add and it is only available on the best quality machines out there but it is still less money than an orbital machine which is usually a nightmare for people.


From contributor L:
I use an old Ramco. The last pass on doors at present is 240 grit (I may jump to 280 or 320). I change the platen on the last pass (these machines use a quick change platen system) to a very soft foam material. The cross grain scratches are barely noticeable, just in a close reflection - the point being the hardness of the platen. It might be worth it to think about a softer platen on the orbital.



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