Down Draft Torsion Box for Marlin Carving Machine

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Project by Thomas Porter posted 01-15-2009 07:09 AM 28095 views 18 times favorited 6 comments Add to Favorites Watch

I bought a Marlin Carving Machine for duplicating mandolin tops in the future. I had built a table for it from the plans that come with the user manual. I didn’t care for it. It’s an odd size so it makes for a lot of waste material and it’s not very sturdy. Also the chips build up when you start carving so there’s plenty to improve on. I wanted a sturdy, lower height table with down draft to remove some of the dust and some of the chips. There will be a huge 8” dust port that runs to the collection area underneath the torsion box. It will angle down from each side to the center where the 8” hole will be.

This is a down draft torsion box top and cabinet to work at a sitting height. It’s got hold down t-slots in three places to help with putting the fixtures down. The cabinet also houses my vacuum pump and tank for future vacuum hold down fixtures. I have yet to try the carver out since I installed it on the table. It’s too heavy for me to lift alone and I haven’t suckered anyone into helping me yet, but I’ll post pictures when it’s all done and hooked up to vacuum. I also need to finish rounding off the edges of the aluminum t-track and give those plugs a finish sand. Just wanted to get some before pictures up there to show what I’ve been busy working on.

-- Thomas Porter, Phoenix, AZ,

6 comments so far

View BarryW's profile


1016 posts in 5190 days

#1 posted 01-15-2009 08:51 AM

One day they’re going to see one machine to woodworkers…we’ll tell it what we want and out will pop exactly what we described…throw wood in one end and Salem secretaries come out the other.

-- /\/\/\ BarryW /\/\/\ Stay so busy you don't have time to die.

View motthunter's profile


2141 posts in 5082 days

#2 posted 01-15-2009 02:41 PM

I am curious to know how much this machine cost you with all it needs to work properly and how well you like it.

I have thought about getting something like this or actually fabricating one for me.

-- making sawdust....

View SPalm's profile


5338 posts in 5165 days

#3 posted 01-15-2009 03:14 PM

Sweet. You do such nice work.

I am not familiar with the Marlin. After Googling, it seems popular with the luthier crowd. Is it a duplicator using the pin on the left as a master? There are no motors, correct (i.e. this is not a CNC)? How does it correct for parallax or tilt?


-- -- I'm no rocket surgeon

View Thomas Porter's profile

Thomas Porter

127 posts in 5415 days

#4 posted 01-15-2009 06:22 PM

Motthunter: I bought this machine used on ebay. I think I paid 500-600. can’t remember. I like it but if your purpose is to do anything other than roughing I wouldn’t recommend it. It’s accurate within about 1/32”. It should be a little better, but for my purposes it will work just fine. I use it to rough carve mandolin tops and then finish the rest by hand.

Spalm: The Marlin is really popular with luthiers who do carved tops or electric bodies, but everyone has said the same thing. It’s not accurate enough to do the finish work, but it saves a lot of time on roughing. I think if I were building electrics I would stick with a pin router for the electronics cavities and neck fitting because the bit is perpendicular to the body and will be dead on accurate. The marlin is really good for signs and carved tops/gradiations because it can duplicate such difficult gradiations. The stylus on the left matches the cutterhead on the right. It’s a black plastic ball on an aluminum rod. It can be removed and others can be placed in to fit other size cutterheads. This one is a 3/4” round. You can raise and lower the stylus so that you can do light sweeps across the blank so that you don’t take on too much material at a time. On mandolins I’ll do 3 or 4 different sweeps so that I don’t push the bit too hard or force the machine across. It should just glide. The trick is to caress your way over pieces so that you don’t create any jerking motion that might jerk the machine around. You can end up with little swirls from the router bit from flex. There’s also some other things you have to be very careful about. If the piece on the left is not exactly the same thickness as the piece on the right, then when you flip it over you will not have a duplication. You have to make fixtures that give you repeatability. I’ve made that mistake and went right through a mandolin top one time. You also have to do some precise measuring to figure out what the true center on each side is.

If you can afford a CNC…. much better. If you’re like me and aren’t ready to do that yet, this would be a good machine once you get a feel for it.

-- Thomas Porter, Phoenix, AZ,

View jm82435's profile


1286 posts in 5026 days

#5 posted 01-15-2009 07:05 PM

That is a pretty cool contraption. Obviously you would need an original to duplicate to use it. I like your downdraft table solution with the t rails for clamping. Have you seen Spalms CNC? You should check it out.

-- A thing of beauty is a joy forever...

View HalDougherty's profile


1820 posts in 4520 days

#6 posted 11-24-2009 04:36 PM

I love the downdraft table idea… Now that you’ve built it, how well does it remove the wood chips? I bought a gunstock duplicator several years ago that works the same way as your Marlin. Only I carve, then sweep the shop…. Oh, and I always have the ventelator on and wear a respirator.

I’m going to build a copy of the Marlin machine soon to make .45 Colt grips. They are only 5 1/2” by 2 1/2” and 1/4” deep so the arc of the router isn’t important. I’ll post a project when the carver is finished. Here’s a few detailed photos of my duplicator:

Here’s a link to the Dakora Arms website. Their photos show the general layout of the machine. Mine is in a room that’s too small to back up enough to get good photos of the overall machine:

-- Hal, Tennessee

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