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Homemade Dual Cartridge Adhesive Gun


Well-Known Member
I installed some doorskins on my chebby project using SEM Door skin adhesive this week. I wanted to use the adhesive when I did my Mustang several years ago but the cost of the gun turned me off. For this project I borrowed my BIL $130 gun, but could only use it for the day, and since I still have plenty of adhesive left and figured I'd finally act on an idea I've had for some time to make one of these dual cartridge guns out of a couple of basic caulking guns.

I started out with two caulking guns that I got at Home Depot ($5.97 ea)

The first thing I did is modify the pivot point on the handle. The stroke for each squeeze of the handle is about a 1/2"... With the pivot point moved up about a 1/2", the stroke is a lot less and give you better control on the material feed.

Once a 1/4-20 x 1.5" long bolt and nylock nut are installed, drill or grind off the head of the rivit and remove it.

Next, cut the barrel of the caulking gun. I used a cutoff wheel on an angle grinder. Then cleaned up the edges and a little around the outer edge for clean welds.

With the shorter stroke, the release lever needs to be adjusted. Since the adjustment bolt isn't threaded too deep, I installed two #10 washers between the spring and the lever to give more preload.

Next up is build the twin ram. The handle portion ofthe ram is too long, so both need to be cut such that the centerline between the two rams is 1.4"
The rams on these guns are around .31" diameter, so from the outer edge to the cut should be about .925"
(.925 x 2 ) - .31 = 1.54"

Just be sure you rams are paralell with 1.54" between the centerlines of the rams.

To build the cartridge housing, I just used 1/8" mild steel from my scrap pile. Two pieces 2"x3.5" and 3 pieces 1/2" by 6.5".
Drill two holes ~3/8" on one plate that will be welded to the frame.
Cut a slot in the other for the cartridge to fit into. The slot was made by drilling a 21/32 hole, then making two cuts to drop the center out.

Next the diameter of the plungers on the rams need to be reduced. I trimmed the flat portion off using a bench mounted shear, then dressed it with a sanding disk.

I tack welded the plate with the two holes to the frame to help align the rams, and then welded the two ends of the rams to form a loop.

A quick test fit, to insure the 6-1/2" long straps would suffice.

Welded the straps on insuring everything is square,

A little primer and some orange finish it off.

The cartridge does fit loose... I wasn't sure if other brands use slghtly different dimensions, so left room to let it float a little. Some adhesive backed foam weather stripping may be used to pad the cartrige some, but I really don't think it should be necessary. So far it pretty much stays in place due to the slot grasping the neck of the cartridge.

The rams seem plenty strong enough for door skin adhesive as it flows quite easily. I don't know if this will work with thicker adhesives, but suspect it will be fine...

With about 2 hours and less than $20, it's not too bad for an occasional use tool.
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