Home Made Nutsert/Rivnut/RIVKLE Insertion Tool

I needed a tool to set aluminum nutserts for various small projects.
I am time rich but cash poor, and I like workshop projects, so …
I modified a “budget” pop rivet hand tool.



These tools are available from “budget” household and auto type shops, and can cost as low as $5.95 (eg Crazies in Brisbane). I chose a type which seemed reasonably strong around the pivot area, as nutserts require a relatively high amount of "squeeze" force to set correctly. Also, the one I chose had a clever “travelling sector” circular arrangement for the pulling cross pin, which would allow for some assembly “fit” of the pull mandrels and associated nosepieces. My “Best Buy” tool was from Supercheap at $14 I think (before seeing it at Crazies!).



The photos show it all really, and variations can be made easily, to suit your need and what is in your bits box. It is not a thing of beauty, but works.


I removed the plastic handle grips, then I stripped the “cacky” black paint with caustic soda.


The original “nose” (into which the pop-rivet tool nipples screwed) of the tool has been sawn off to allow a 3/8 in. BSW black nut to be silver brazed onto the remaining 20 mm length of the nose. This holds the new anvil nosepieces, made from 3/8 in. BSW hex set screws, sawn off to give 8mm or so of thread, and each “drilled to size” for the anvil face end of the mandrels, and back drilled oversize to within 3 mm of the nosepiece front face to allow some angular and axial mandrel clearance whilst in use.



The nut, now on the tool handle, which holds the nosepiece, has been drilled out on the front face with a 3/8 in. drill to a depth of about one thread (1mm or so), to allow for the unformed part of the rolled thread on the nosepiece bolts, just under each head, and this allows a snug fit of nosepiece back face to the tool. Best to fasten the tool handle down very securely when doing this in a drill press, and use the drill depth stop facility, or else the drill bit will grab the work, with interesting results. This is a job type where we all need left hand drill bits. I think I drilled mine by bolting down the work in vice to the drill press table, and turning the drill in chuck by hand; safer.



The mandrels are made from 50 mm of 1/4 in. BSW mild steel threaded rod, silver brazed onto the heads of HT bolts and machine screws, and slotted for a screwdriver with a handsaw in the 1/4 in. rod end.

Each mandrel is ground down at the braze joint to allow axial entry into the nosepiece hole, before the nosepiece is fitted to the tool. As the nosepiece holder nut is 3/8 in., each mandrel braze joint (and screw head) is ground down to about 6.1mm dia. if required at all. Ensure the braze joint is “full”, by coating the job ends with braze fully first, then “sweating” the bits together end to end.



I made mandrels for -
6mm - 40mm screw, 90mm overall
5mm - 45mm screw, 95mm overall
4mm - 40mm screw, 90mm overall
3mm - 35mm screw, 85mm overall
1/4 in. BSW straight rod, 95 mm long overall.


An 8mm threaded rod mandrel (as yet not made) will just fit through the 3/8 in nut with no nosepiece. This should work, albeit with a little bit of slop. Best to use a low fit class of screw here to clear the threaded hole.
I will use a “bolt and nut” method of setting my 10mm nutserts if ever needed.



The “wing nut turn screw” is made from a 1/4 in. BSW black nut and 1/4 in. wing nut both silver brazed onto a 22mm length of 1/2 inch tube, all from the bits box. The wing nut is drilled out for a generous 1/4 in. clearance, after brazing. I filed out the round cutout on the top handle near the pivot area, so the wing nut turn screw had a bit more clearance when the handle is open.



The original tool cross draw pin has been replaced by a 3/8 in. BSW bolt 50mm long, which gives an unthreaded length, “just a smidgin longer” (highly technical term) than the overall width of the larger handle, and secured with a 3/8 in. nylock nut. This bolt is drilled out with a 1/4 in. drill, at a point which lines up with the axis of the nosepiece hole. I used a mild steel bolt, but may have to change to a higher tensile Gr. 8 bolt later, if my current cross bolt bends over time. I used thin 3/8 in. washers on the cross bolt, between the two handles, to avoid handles binding, and to centre the pull mechanism. I had to cut one side of each washer for fit with the cross bolt. Best to have a little clearance around this area, but not too much.



After finishing up all parts, and cleaning (with clothes washing detergent and boiling water), I painted my tool with Cabot’s Crystal Clear lacquer (a product from heaven), and pushed the plastic handles back on.

This tool works a treat on aluminum inserts, and works OK on 4mm steel inserts, but I think it would stress the tool too much with 6mm or larger steel inserts.

Practice using the tool to judge the stroke length and force. Adjust the turn screw so as to leave a full thread protruding on a new nutsert before squeezing, and enough grab by the handles, before setting the nutsert.

Use a flat screwdriver to remove the mandrel from the nutsert, after setting.

Threaded insert/nutsert/rivnut/RIVKLE data is available from BolHoff and Avdel, websites, et alia.


Watchpoints and Hints-
Disassemble the original cross pin from the pop rivet draw tube, by using a 6mm flat screwdriver in the slot on one side of the pin, and turn the pin 90-180 degrees, then push the pin sideways. This is not obvious until seen disassembled. Clever.



Drill the nosepiece pilot hole before sawing the bolt down to size, so as to allow holding the bolt fully in a drill press vice, or other, and this maximizes drilling accuracy.


Drill the nosepieces undersize first, then slowly increase the drill size so as to eventually give minimal clearance of the mandrel through the nosepiece face. Failure to do this will mean that when using the tool, inserts can deform into an oversize nosepiece hole and give a bad result.



For brazing the nosepiece nut to the tube, use a "longish" scrap 3/8 in. bolt, so as to align and centre the axis of the nosepiece nut hole with the tube hole. Use the same method for the turn screw and nut.


Make sure you use a "thickish" washer under the wing nut turn screw for load distribution on the cross pin.



I did not reuse the original handle spring, as I had drilled out the retaining rivet, and found it better for me with this type of tool to have the handles non sprung.



I used Comweld SBA 245 silver brazing rod, and associated flux, for this job, as it flows well at low temperatures, and I can use my small Kovea butane hand torch. As I understand, the tensile strength of this brazing metal in bulk, is about 500 N/mm^2, which is about 70,000psi. This is more than mild steel and should be ok, but as per the photos, I made two mandrels for each size to allow for “the variables of life”.



If I was starting a new job, I would probably –
- Use HT 1/4 in. rod for the mandrels and HT for the cross bolt.
- Think about using a knurled knob on the mandrel top??
- Use two 3/8 in. nuts for the turn screw to reduce the wear on the mandrel and turn screw.
- Consider strengthening the handle work ends by brazing 3/8 in. steel washers to the handles at the pivot pin and cross bolt points.
- Add a stroke limiting adjustable screw thing to the top handle?


If you think that this post is a bit long winded, you are correct, but I am trying to post it all in one attempt.



I just saw that commercial types of nutsert tools are selling on eBay for $55 ex UK et alia, including a small handful of inserts; groan…


Cheerio, Mike