A simple solution for holding a soldering iron when inserting brass threaded inserts into 3D printed items
NOTE – This is a revised posting with a modified write up.
When faced with adding threaded holes into 3D models I am faced with three choices.
The easy option is to model the threads in Fusion 360. This is fine for a ‘fit and forget’ single fastening but for repeated screw insertion and removal the modelled thread will begin to wear.
My preferred solution is to use embedded nuts in the plastic or leave an open hex cavity to fit a nut into after printing. Some jobs do not have enough space to use the embedded nut technique so brass inserts are the next choice. Brass threaded inserts come in a number of sizes and geometries and are available from Amazon and other sources. The inserts are melted into the printed medium with a soldering iron or other such heat source.
Having had mixed success with a handheld iron I pondered for a while with Fusion 360 whether I could make a jig to improve insertion repeatability. This led to some internet searching and finding a couple of solutions. The first one was via Clough42. He showed a heavily engineered solution supplied by Naomi Wu.
Naomi’s product was impressive but seemed to be way over the top. Next up was a site by Valera Perinski. His site is remarkable and oozes all manner of 3D printed objects, one of which was just what I was looking for – a simple insert punch.
Valera’s design, while simple, looked elegantly functional. I downloaded the STLs. Valera offers these free of charge with a comment that he would appreciate any contributions. A contribution was duly made. Thank you Valera !
My modified version of Valera’s design is shown above and is described in the attached ZIP file along with the my versions of the 3D print STLs.
It had become a standing family joke on steaming outings that my Polly V whistle left a lot to be desired. Quite often it would do nothing more than a feeble splutter. The Polly V kit supplied whistle is fitted under the running board on the left hand side of the cab. The pipe run is long and somewhat tortuous. I had insulated the pipe to reduce feed loss but this made little difference. The whistle valve also had a gentle leak and was very stiff to activate. All in all not a good setup.
A recent article in Engineering In Miniature (EIM) by Richard Wightman (September 2022) went into detail about a whistle and valve combination he had created. The whistle was fairly conventional but very compact. The steam control valve was unusual in that he used a standard tyre Schrader valve. This tweaked my interest and I set about upgrading my Polly V locomotive using this technique. Here are some Fusion 360 images and shots of the new valve and whistle mounted in place on my Polly V.
Here is a blow by blow description of the process as a PDF download.
Each of the axis locks on my VMB mill uses two M8 cap head screws in association with a lock nut. This works OK if the hex driver is in reach …. but it never seemed to be …. so I decided to remove the cap head screws and fit lock levers instead. Lock levers come in male and female format and various thread sizes. The M8 versions all have 40 to 50mm long lever arms. This length doesn’t work comfortably in the space constraints on the VMB X and Y axis but is fine for the Z axis. Similarly I also had to reduce the length of the lever thread.
The obvious solution was to cut down the length of the lever arms. The trouble with this was the raw open end of the arm looked naff and did not sit easily with my usual perfectionist approach. The solution via Fusion 360 was to create some 3D printed end caps which I then bonded in place with Araldite. This finished the job properly.
The Fusion 360 3D modelled end cap printed in under 4 minutes with a further 5 minutes for the Araldite to cure. I now have a much more elegant looking solution.
All of which has led to a rethink the lock levers on my Quorn tool grinder. I get in a real mess with these clashing with each other. Where did I put the Araldite ? …..
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A 3D Printed Version of John Moran’s Drill Point Inspector
John Moran has an excellent website that details all manner of engineering projects. He is a keen advocate of four facet sharpening of drill bits and he details a Drill Point Inspector device for checking grinding results. I quite liked the concept and thought it would also be a useful asset for checking the condition of milling tools. The design uses a small inspection eyeglass magnifier lens that can be flipped from end view to side on view for tool tip inspection.
Those who know me through my blog will know that I am of a lazy disposition which tends to cause me to step back and look for an easy way to manufacture something. John’s design immediately suggested to me that a conversion to a 3D printed equivalent would be a practical solution. I also picked up on a comment that John made that you needed good light to be able to view the drill point clearly. As a result of this comment, the 3D design evolved with the addition of a simple LED illuminator. I also added a ‘right angle stop’ so that when hinged for side viewing, the lens was held more repeatably.
Because the inspector will only be used now and then, I opted for two small hearing aid batteries as the LED power supply together with a single resistor and switch. I printed two slots in the cavity for a pair of nickel silver battery contacts to sit in.
The design was modelled using Fusion 360. The two parts of the body were 3D printed. The Perspex viewing graticule was CNC milled to size and the reference comparison lines were also engraved on the CNC. The inspection lens is available from many sources on EBay (x30 21mm). The inspection screen mounting holes are 3D modelled. Here are a couple of shots of the finished model.
Note that the addition of the LED illuminator needs the modelling of a cavity on the bottom surface of the main body. When printing this part it will be necessary to have the printer provide support structures. I also printed a cover for the cavity but this could be an offcut from an old credit card or similar thin plastic sheet.
Once printed I found the parts needed slight ‘fettling’ to remove any surface striations on the V block section, in and around the hinge section and around the eyeglass mounting slot. That aside it printed fine and the parts went together easily. More to the point it works well and is a useful tool to have to hand.
The Fusion 360 file and STEP files for the main two model parts are available in the following ZIP file. If you need additional information please get in touch.
First of all an apology … colour has arrived as I have finally migrated to the WordPress Guttenberg editor from the Classic Editor. The Classic is due to be phased out in the near future so I thought I had better jump before I was pushed. I can see the advantages this offers but I am still getting to understand the different way of working.
That aside, onto the post …
The problem with creating 3D knobs is that they can lack robustness unless they are made less dependent on the printed material. There are various ways round this but the easiest method I have found is to embed a conventional metal thread or nut combination. This allows you to be as stylish as you want with the shape of the knob while knowing that the core locking material is resilient to twisting.
A couple of good examples that I have produced recently are a replacement knob for holding the cover of my BK3 bandsaw in place and one to allow hand tightening of a U bolt clamp to a pipe.
The BK3 clamp required a protruding thread (male) while the U bolt clamp needed a female style. Both were designed in Fusion 360 and embed either a nut or a thread and nut combination as the following images will show. The basic form of the knob is similar in that is has a cavity for the chosen nut size and for the female form may or may not have a through hole. The 3D printed body can be as fancy as you want to make it. I have been pleased with the basic shape shown below as it allows a firm grip to be applied.
Depending on how tight you can make the fit of the nut, the female form may need a dab of SuperGlue to hold the nut in place in the printed body and the male form will need Locktite on the thread and nut.
While both of the versions shown above have a boss for the nut cavity, this could equally be inset into the main body of the knob so it finishes flush. Next time you shorten a screw, save the thread offcut for future use on a knob.
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