Weldmount Fasteners

G

Grazer

New member
I have a quick question for any of you who have used these acrylic bonded fasteners in your boats. I have used them to bond some items in my boat to fasten starboard, chargers, footman loops etc. My question has to do with cutting off the threaded bolts as the "meat hooks" are too long. I am thinking that, like epoxy, any heat added to the bolt through the process of cutting off (grinder, dremel) the bolt may weaken the adhesive properties of the cured bond. Has anyone done this? I am going to write the company as well and query them too.

Thanks,
Grazer
 
I've used quite a few of the studs and have cut off many (since they only come in limited sizes, they are often a bit too long). However, I have cut them off before installing them, so I can't address your question. The folks at WM are very helpful though, so I think calling them is a great idea.

Sunbeam

PS: I would definitely call WM first, but I guess what I would do if I "had" to cut one off after installing them (and say I had no telephone ;)), is use a Dremel or Roto Zip with a heavy duty cutting wheel, putting a couple of nuts on between the part you are cutting and the base, perhaps with a Vise Grips attached (to dissipate heat). Then too, the nuts will help "chase" the threads when you remove them after cutting.

I also suspect the glue is not as vulnerable to heat as epoxy, but I don't know that and like you, would do some research. Edited to add: Not sure which adhesive you used, but the TDS I had saved for the AT-1030 says that the cured adhesive has a temperature range of -65ºF - 250ºF
 
I've also used quite a few weldmount studs and have trimmed a few after the fact without problems. For example, I mounted my NMEA 2000 connectors with some 10-24 3/4" weldmount studs to the helm bulkhead inside the v-berth. Since this was in the v-berth I didn't want any "meat hooks". I mounted the studs, installed the NMEA 2000 connectors, threaded on the nut and then marked the cut location. I trimmed it with a small hack saw and the heat never traveled far enough up the bolt to even warm up the base. I think you'll be fine unless you plan to trim with a plasma cutter.
 
I'd trim prior to attaching as I find it easier to put the part in a vise and do so. I usually use a cutting wheel on a dremel tool and then a grinding wheel to taper the edges. Also, if there's space, I recommend putting a die on the threaded part prior to cutting. That allows you to easily clean up the threads after you're done.

On a related question, how many remove the gel coat prior to attaching and how many just attach directly to the gel coat?
 
Thanks for all your responses. I did contact the folks at Weld Mount and they provided the following:

"You won’t affect the adhesive unless the temperature reaches 300 degrees F. That’s pretty hot for a grinder. I would recommend that you thread nuts tight to the baseplate and up the thread to just below the point you want to cut. Use the grinder to shorten the stud. The nuts will better support the studs and help dissipate the heat. Once the stud is at the correct height back the nuts off. These will act like a tap and clear the threads as they come off. Should be no problem."

In hindsight, I wish I had measured and cut them off prior to installing. I like the idea of using a hack saw to reduce the head produced, however the space required to move the tool is limited, so I'll be forced to use the dermel.
 
rogerbum":gb6bf2fa said:
On a related question, how many remove the gel coat prior to attaching and how many just attach directly to the gel coat?
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For me, it depends. If what I'm attaching is relatively light (ACR, buss bar, even the trim tab HPU (but I did use four studs), then I'll go right onto the gelcoat. But I do prep pretty religiously. I solvent wash with Interlux 202 and a bevy of clean towels, then sand, then solvent wash again (just denatured alcohol and not worried about wax this time).

I had considered mounting the trim tab planes with Weld Mounts and I did a few experiments on a scrap piece of boat fiberglass. One I mounted right to the gelcoat; for the second one I removed the gelcoat and mounted to the fiberglass underneath; the third one I screwed (used one of my cast off interior cabinetry angles) through the fiberglass and into a block of wood to simulate a fastener into core.

Once these all cured I put the glass in a vise and hung lead weights from them. This was a static load but I was curious. I forget now, but I think I got up to 150# or so and nothing budged. Next I started banging on them with a 5# sledge. Of course I didn't measure this in any way, but the one on the gelcoat came off first. It did take a few bangs, but not really hard ones. Most of the gelcoat stayed attached to the WM stud, so in other words the gelcoat bond to the underlying fiberglass failed first. Next I banged on the stud glued to the fiberglass. That one eventually failed but took considerably more force. When it did come off about half the glass was still bonded to the stud, and the other half the glue had stayed attached to the fiberglass piece. So a fairly "even" failure. Then I banged on the angle screwed into glass/wood. That one bent without failing.

Ultimately I decided not to use WM studs for the trim planes, mostly because I really had no way of knowing how much force they needed to withstand and I didn't want to wonder about them. Instead I overdrilled very generously, filled in with thickened epoxy, and then tapped for 1/4" bronze fasteners.

I have had a few WM stud failures, but they were on very light components and it was traced back to a faulty batch of adhesive (the glue failed, not the gelcoat/glass). Now I first make a test batch of adhesive before adhering any parts with it. The adhesive is somewhat picky about temperature/storage, and although I was careful about it I had no way of knowing where it had been before I bought it. WM worked with me on it.

Sunbeam
 
Sunbeam":1bk65gu4 said:
I have had a few WM stud failures, but they were on very light components and it was traced back to a faulty batch of adhesive (the glue failed, not the gelcoat/glass). Now I first make a test batch of adhesive before adhering any parts with it. The adhesive is somewhat picky about temperature/storage, and although I was careful about it I had no way of knowing where it had been before I bought it. WM worked with me on it.

Sunbeam
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The adhesive I bought through mail order arrived and was past the expiration date, after consulting with WM and conducting test batches myself, the product worked as it was supposed to and has bonded well. I remove the gelcoat down to the fiberglass, clean with acetone and adhere the stud or footman. The "well" produced by grinding down to the glass creates a surface that is fair to the surrounding gelcoat.
 
Grazer":2rmh8nla said:
I remove the gelcoat down to the fiberglass, clean with acetone and adhere the stud or footman. The "well" produced by grinding down to the glass creates a surface that is fair to the surrounding gelcoat.
Click to expand...

That's a good way to do it, and I will probably use this method for some of my installations. Sometimes it's nice to have a flush surface. Unless I change my mind, I'm going to mount my Starboard™ transducer block to the gelcoat (four studs), and for that I drilled a bit out of the block with a Forstner bit so that the block would sit flush to the transom. I may change my mind and remove the gelcoat though.... guess we'll see when it comes time to mount it.

The one thing I would do differently from what you described above is to solvent wash (I like Interlux 202) prior to sanding, with plenty of clean towels. I like to be sure no mold-release or gelcoat-air-inhibiting wax is present (amazingly, it is still alive and well on 40-year-old boat hulls that have been in the water, and often causes coating failures there). The wax we add for protection later should have that staying power!. I believe there was wax added to even the "duller" gelcoat on the interior of the C-Dory hull (to inhibit air so it would cure), although I'm not sure. So I de-wax.

Sunbeam
 
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