Swann Morton Retractaway Review

 

I've loved Swann Morton for years ever since using the old school burnt orange model makers blade holders they made for many years as a kid. I recently came across the "retractaway" blade holder in a makerspace toolbox and was immediately impressed with how it felt in hand and secure the retracting mechanism was. So I ordered one and have had it for a couple of weeks. It's a pleasure to use and after years of scalpel holders in toolboxes that may or may not retain their cap/cover its nice to know this is safe when chucked in a box. 

Not much to say technically apart from its only designed to be used with a small range of blades. 10, 10a and as luck would have it 11 and 15, the latter of which is my favourite and is the fitted blade in the image. It has 3 idents on the retracting mechanism, closed, half open (the working position) and fully open (the position for swapping blades). Retention is great albeit with a slight bit of side play in the blade assembly. In usage though this rarely causes any problems and it's capable of very fine work.  

FreeCAD Laser Cutting Addon Workbench

Just uploaded my latest video tinkering with FreeCAD in which I explore how to install add on workbenches and we install the Laser Cutting Interlocking workbench and take it for a spin using the automated tools for adding interlocking tabs and holes to our models and how to automatically lay out 3d assemblies into 3d parts for export to an SVG.

Inkscape SVG to FreeCAD

On a bit of a roll with videos this week! After I put up the video about the longworth chuck mechanism as a robot gripper, a follower on twitter enquired about how I had approached importing an Inkscape SVG file into FreeCAD (which I had done due to laziness as I didn't want to totally redraw the longworth mechanism)! Seeing as he asked nicely I did this little walk-through. As I mention in the video, its a useful fix but its definitely preferable to only use this when needed as directly working in FreeCAD using sketches is more dependable. Hope it's useful. If it is do feel free to show your support via my ko-fi page here!

Longworth Robot Gripper

Devout long term readers of this blog may remember my longworth chuck design and build which got re-hashed relatively recently into a dividing tool (as seen in Hackspace magazine issue 29 article on dividing which also has links to the project files on thingiverse). I've been interested in its application as a robotic arm gripper for a while and decided to prototype a servo driven one which might be able to be mounted on the opensource Modular Tracked Vehicle (MTV) robot as featured again with all the design files linked in hackspace magazine issue 32.



I'm pretty pleased with this first pass prototype (as usual with heaps of hot glue etc) and I'm going to continue to develop and refine it a little as I think it could be quite a fun gripper type for people interested in robot challenges etc to think about using. Check out the video above to see it in action and feel free to subscribe to the Youtube channel.

3d Print Welding and Fibreglass

New little video I've edited today chatting about some 3d printing techniques, welding parts with a 3d printing pen and also embedding fibreglass into prints to make very stiff components.

FreeCAD video part 2

I've really enjoyed making these videos for the Ffiws project from Arloesi Gwynedd Wledig and its been a welcome opportunity during lockdown! Building on Part 1 we move to the part design workbench and build a part using the "body" concept, mapping sketches to faces and using tools like the pocket tool and hole tool to create a nice model. The model is a part of the larger MTV robot project I built and wrote about in Hackspace Magazine.

Printing Pinion Gears for the mini lathe.

I managed to strip one of the pinion gears on the mini lathe a while ago and I was surprised that I couldn't find a 3D model of them to print, particularly as I'd seen a lot of gear wheel sets for the mini lathe on thingiverse and elsewhere (I think this is an indicator that perhaps other people aren't as idiotic as me and don't strip their pinion gears)!

 Today I set about sorting it with some 3d printed replacements. I used the involute gear tools in the "Part Design" workbench of FreeCAD which I am using more and more as my go to CAD environment. It's a pretty easy tool to use so long as you know the "module" of your gear which can be worked out as it is the pitch circle diameter divided by the number of teeth. Counting up the teeth on the old stripped gears showed they were a 25 tooth and a 20 tooth and the overall diameter was close enough to make me feel that the pitch diameter was going to be the number of teeth in mm giving a module of 1. I'd read online that the mini lathe gears all ran at 20 degree pressure angle. A quick bit of calliper work on the hole diameter and we were ready to CAD!

The results are great, printed in PLA at 35% infill I've been running the gearbox for a couple of hours and all seems well. I've printed up a few spares and chucked them in the box of gears. As I couldn't find this set of gears online anywhere I've put it up on thingiverse as a project so hopefully it's of use to others. You can find the files and the print settings here.