Problem downloading STL file to convert to cut on S3

I am restoring an old Craftsman bandsaw for our MenzShed but the blade guides are missing and no longer available. I thought of trying to design and cut replacements on my S3 but dimensions would be a bit hit and miss with no pattern.

I have found a file on Thingiverse where the contributor has designed and produced a version on a 3d printer and has made the STL and Sketchup files available for download. He has installed them and they work fine so design must be close to original,…

I have tried to download the STL to convert to a vector file to cut some from HDPE but when I try to open the file I get a message:
“Invalid Public Key Security Object file
This file is invalid for use as the following: Certificate Trust List”

A look at the file in preview it seems to be the Trust Certificate and not the actual STL file.

Any idea what I may be doing wrong and how I can get the STL?

If you dont get a good answer look at youtube. I have seen several people make cool block holders for their older bandsaws.

I was able to follow your link, download the file and here is a screen shot of the block:

The object opened up in a 3d viewer I have on my Windows OS. So try to download it again.

You need to associate .stl files with the software tool which you wish to use to open them — or don’t open it when downloading and just save and then process the file in the tool which you wish.

Hi Will/Guy

I did not try to open it…just download it so that I could import it in to Inkscape. It appeared to download but in File Manager the download shows as Type = Certificate Trust List. I associated it with Inkscape which made the file type change to STL but its not a normal Inkscape file type so I did not expect it to just open

I managed to download the STL file fine on an Android tablet so I emailed it to my Gmail and tried to open it again from there but got the same message. I cant save it from Gmail to import it in to Inkscape so I downloaded a couple of free STL viewers (Materialise Mini Magics & MeshMixer) and it opens ok.

The strange thing is that MMM shows quite an angular view(which I expect) but Meshmixer has much more rounded edges.

Anyway all seems to be sorted now thanks to you and Guy. Just need to work out dimensions and steal an HDPE cutting board from my wife :slight_smile:

I have never made a block for a bandsaw from scratch but why are you going to use HDPE. I thought HDPE was easy to melt. Have you thought about trying to buy the larger Olsen Cool Block and machine that down to your size.

Let us know if your HDPE blocks work but I have seen blocks made of aluminum. You could use the painters tape and super glue to hold down your work. Just machine slowly to keep the pressure off the piece.

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I originally intended to machine from aluminium as that appears to be what originals were. The 3d printed ones seem to work so I thought I would try HDPE as prototype.
Unfortunately there are no aluminium suppliers where I live and out of town suppliers prepared to supply seem to only want to sell commercial quantities. HDPE is easy to get so I can afford a few mistakes until I am sure design is working and maybe locate a source for aluminium.

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