Screw polishing frog

[Waggy]

I recently watched a YouTube video (see below) on screw polishing and in the more information section there were instructions on how to build a screw polisher, I decided to make a 3D printed version of this tool based upon these instructions (pdf instructions of brass tool attached - credit or original author):

Here is the version I created based upon the brass tool instructions and instruction from the video - I had to change some of the design aspects based upon the different requirements needed for 3D printing, but the essence of the design and key features are kept:

Here is the top of the tool (prototype):

Here is the underside:

I have used M3 bolts throughout (see parts list below) and reinforced the areas under the bolt heads with a standard M3 washers, here is the FreeCAD view showing the complete assembly:

Here is the "Bar" section:

Here is the body "Frog", the slots in the top and back are to insert the 'trapped' M3 nuts (point down)

Here is an x-ray view of the complete assembly:

I used M3 wing nuts as locking nuts to prevent the bolts (legs?) backing off during use, I also included a cutout in the top to insert a bullseye level (10mm x 6mm) which hasn't arrived from Amazon yet, and so is absent from my pictures.

Parts list:

• 2 x 40mm M3 Stainless Steel 304 Hex Socket Head Cap Screws Bolts
• 4 x M3 Stainless Steel 304 washers
• 1 x Mini Spirit Level Bullseye (10mm x 6mm)
• 2 x Wing Nuts M3 A2 Stainless Steel Butterfly DIN 315
• 4 x Hexagon flat nuts A2 Stainless Steel M3
• 2 x 30 mm Fully Threaded Allen Key Hex Socket Cap Screws Bolts M3 High Tensile

I have uploaded the design to printibles (link here), but will include the file here also, I'll attach it as FrogV2.pdf so I can upload here, please download and replace .pdf with .zip to access.

3D printing settings:

• Material is PLA+, just what I had on the printer at the time, could also work with PETG etc.
• Fill is 75% gyroid, setting is high to ensure rigidity of the tool during use
• 1.6mm wall thickness, setting is high to reduce wear on faces which interact with metal parts.

 

Here is the missing bullseye:

 

Here is the link to the youtube:

Enjoy!

how-to-make-a-bolt-tool.pdf FrogV2.pdf

Edited March 22, 2024 by Waggy

[luiazazrambo]

Hi Scott, many thanks for the above! What is your experience with your printed bolt tool so far?

[Waggy]

On 10/26/2024 at 12:36 AM, luiazazrambo said:

Hi Scott, many thanks for the above! What is your experience with your printed bolt tool so far?

Hi there, I have used it a few times and with the inclusion of the bullseye spirit level it's far more useful. I have found the v-notches to be a little too large in most cases, and If I get the time I may re-design the part to both reduce the size and place them on the 'bar' instead of the body, then if they are too big/small I only have to change the bar and not the whole body. I'll keep thin in mind for version 2.... but I'm in the middle of changing jobs/industries and moving back to the UK at the moment, so rev 2 may be several months away.

[mikepilk]

I made my own from brass, with just a saw, drill and files.
It's surprisingly quick and easy to use, just a minute or two to polish a screw. (Using 9, 3 and 1 micron lapping film stuck to glass).
The 'v' slots need to be very small to hold the smallest screws. I just use a fine file to score a line.

I don't see the need for a spirit level (could it be accurate enough?). I just set the adjustable screws by eye, drag the frog once over the abrasive, see where it has rubbed the surface, and tweak the screws. 

[Waggy]

@mikepilk great job