Buy the plans here: https://miscpro.com/shop/
In this video I’m going to assemble a 3D printed drill guide – that I designed in fusion 360, and 3D printed on my heavily calibrated Prusa mini aka the prusa little s%^t. I’ve wanted one of these for a while now, but the high-end model from Axminster Tools is just never in stock, so I decided to build my own. The parts are printed from PLA with a rectilinear infill of between 30% and 50% depending on the part use – so this is a test of concept although spoiler alert, it does work.
I’m using commonly available fixings, and kinematic parts such as 8mm linear rails and polymer bearings. And innovatively I might add, I’m also using metals kitchen shelf pins, as alignment and pivot pegs. This felt like such a good idea I bought 1000 of them from ebay for around £15.
I began filming this video from my flat during the lockdown in early 2021 – but I have subsequently been summoned back to work as educational institutions have reopened in the UK, and I’ll probably end up finishing the video back in the studio one weekend, ready for the fourth lockdown.
I’ve also made this into a downloadable PDF manual, which can be purchased along with all the relevant files from my website. You didn’t think I was going to give you this for free, did you? Anyway carrying on.
I’ve made a few different versions of the parts while designing the tool, but the most elaborate base which I split into four parts with their own alignment holes. I did this because I was having problems printing to the full bed size of the prusa little s$%t, with parts of the first layer lifting. This was particularly noticeable on the righthand side where the bed high sensor doesn’t reach. I aligned the pieces with the metal shelving pins and glued them with dichloromethane on a granite kitchen worksurface, trying to keep the base flat.
This didn’t work as well as I’d like and I noticed the base was rocking, and not in a good way. I was about to give up but decided to print the part again in one go, but this time to reduce the recommended speeds to 25%. It took a couple days but the new base was much better.
I’m using Ooznests PLA to print with, which is a pretty good quality filament and also comes on a cardboard spool so there’s less environmental waste.
So I got about this far with the segmented base but what I found was gluing it together, the edges, the edge faces, weren’t parallel. They produce a joint which wobbles. So I had another crack at printing the base in one go and I managed to do this which is a lot better. And the secrete was to print really slow. So I will dismantle this and fit the pivot sections onto the new base. In the meantime I just made a very nice roast vegetable soup and my oven is warm and I’m going to use the residual heat to fit a bearings onto the shaft which will have the chuck at the end.
But first let me recap – I dismantled the salvageable parts from the first attempt and carried on with the chuck shaft – which has a B10 tapered end. I bought that from banggoods but the chuck I’ll be using is from my old micro bench drill which has a 0-6.5mm opening. That’s a bit small for a useful drill guide but I’ll use what I have for now and can always get an adaptor collet and swap over to a B12 0-10mm chuck in the future. I could also swap the shaft out with an ER collet extension, which are more readily available in different sizes and lengths.
You may have noticed already that I’ve put the insert into this 3D printed part and I did that with one of these. Which is a modify 3D pro which has a special end that sits into the threaded insert and heated it up while it is set. I used two different types of see what I preferred.
And those mounting points could be for attachments to the jig such as extraction nozzles or what I had in mind – a dedicated clamp for the heated threaded insert tool which I’d imagine would make the task more evenly. You can see what I had in mind on the 3D model. As of yet I still haven’t printed that part out.
I’m using 6000 2RS series bearings. These are 10x26x8mm which I’ll lock into place with a couple m10 locking collars at either end to clamp the shaft in place. I checked all the bearings for tightness and warmed one up that didn’t quite fit – pushing it into place after the locking collar for the bottom piece and leaving it to cool – thus the silly oven-gloves.
The other thing I need to do, is to fit the bearings, these polymer bearings into this section here and to clip them in place. Or lock them in place with the circlip. And there is a bottom, the hole is slightly smaller here. It’s a recess just to stop them from being pushed out.
You see the first ones in, and it’s the same again using this special pliers that first on the end there. Just make they sit in their slots – that was very satisfying.
It then turned out that despite the bearings being cool to the touch, they could be slip off the B10 parallel shaft, so I push-fitted them into position on the 3D printed part which I simply did with a clamp and placed the chuck shaft with locking collars in place.
When knocking the chuck onto the tapered shaft – you want to make sure the jaws are fully opened so you are not hitting and damage those. I should have really used a soft-face mallet, but I’m using what I have, which is this rather unusual hammer.
If you are wondering what this unusual hammer is, it was my godfathers before I nicked it from him. And he made it while at school when they use to do Design Technology classes. I remember finding it at his, and feeling a but curious about it. So it’s a little rock hammer or something like that, and you can see it’s been used quite a bit. And the handle is just bits of plastic acrylic which has been turned with a brass end. And it’s actually lasted quite well considering it’s probably 50 years old.
I’m now carrying on with the assembly fitting the trunnions onto the base. Under those segments are two captive nut which can be used to attach centring pegs or other attachments from underneath. It’s so good having a 3D model so I can cut away to show you things I forgot to film.
For the pivoting section I’m using countersunk machine on either side, to maximise the space between the two pieces. While the linear rails slot from the top and are clamped in place. I was going to glue these parts in and later decided to make it all modular in case any parts needed to be replaced.
These are my 8mm linear rails. One came with a bit of rust on it which is a bit annoying. So these slot into place and a 25mm lock screw secures them.
I then installed the sliding carriage – which is ever so slightly tight at the bottom. I may have pulled the parts out of alignment with the fixing machine screw or while printing the orientation of the part while printing may have caused the parts to be slightly different – I am after all using the Prusa Little Parts Parts Parts Parts Parts Parts Parts. All that said it still slides and feels very rigid.
For additional rigidity I made the top brace connected with an arched bridge. Typically most designs have this separate but it made sense to design it this way considering the material I am using.
That is pretty much the completed tool. I have centring pins which attach to the bottom and can be used to centre the drill chuck to two sides faces – such as a door when drilling a hole for the locing barrel. And there’s also depth stop clamps which attach on either side rail to allow for repeatable drilling depths. So overall it probably looks like the best thing I’ve ever made.
The next thing is to plop a drill on the end and look at how centred the chuck is.
Which by the looks of it, is pretty bang on.
If you would like to build one of these too you can download the plans and all the relevant files from my website www.miscpro.com/shop – the manual is actually even better made than this video so I’d highly recommend it. If you’d liked this video please smash the living bejesus of the thumbs upwards button, and write the words stinky cheese in the comments. If you didn’t like it press the dislike button but remember the algorithm gods are watching yooou.
Until the next one take care.