Affordable custom metal parts

[hucklefish]

In the morning, Ratsun!

 

I just want to share a pretty useful resource I found recently: https://sendcutsend.com/

I've made a throttle cable support bracket for the Nikki carburetor on my 520 using this service, and I've got the pieces for an alternator bottom mounting bracket. Full write-up on the alternator mount following, and for pictures of the throttle cable bracket from 3d printed prototype to metal pieces on the truck, see my post linked at the bottom of this one.

 

First, the important little details you might be asking by the end of the post. I have 26 years experience as a drafter, mostly in AutoDesk products, and now that I've escaped full-time desk-sitting forever and no longer have access to the "real thing" I use ProgeCAD, which costs about $200 for a license, looks and feels almost identical to the latest version of plain vanilla AutoCAD, and has an FEA module and some other interesting looking tools available for additional licensing fees.

My 3d printer is an unmodified Ender 3 Pro, I use Cura 4.10.0 for slicer (Windows 7, can't upgrade), and I'm printing lately using Polymaker PLA+.

Sendcutsend has a minimum order of $29, which includes shipping, and these two projects cost me $29 (alternator bracket) and $30.71 (throttle cable bracket). One thing to note is that Sendcutsend provides an estimated shipping date, and for some reason I thought that was an ETA, but it's actually when they expect to ship the order out. Shipping took less than a week if I remember right. I could have paid extra for express shipping, but there's no speeding up the manufacturing - it's first come first serve.

 

My 520 came to me with no top alternator bracket and the bottom of the alternator mounted in a weird looking double bent plate pair bolted to the motor mount. The alternator hda a pretty noticeable front to rear wobble which I thought was probably because it was only held by those 2 bolts pinching two 3/16" thick plates against one of the plates of the motor mount. It also came with what appeared to be a lawnmower belt running the alternator and water pump, and when that disappeared somewhere between here and Home Depot, I replaced it with the proper belt, and the wobble went away. But before that happened, I had already designed a more correct bottom alternator mount and sent off the order to sendcutsend.

 

To get the dimensions of the mounting holes, I held this piece of cardboard against the straight edge running along the side of the engine block right below the original mounting holes, and tapped all around them with the round head of a ball peen hammer until the holes and their bosses were well marked on the cardboard, as well as a small rectangular boss above and slightly to the rear of the bolt holes.I think the 2-7/8 note is the distance between the two lower holes, as measured by holding a steel ruler against them.

 

To get the dimensions to and orientation of the desired position of the alternator bottom mounting hole, I found this piece of cardboard with its handy 90° crease already made, and held it against the rear face of the existing alternator bracket and the tab at approximately 90° and positioned over the lower forward bolt hole (the one circled in the previous picture. I measured the thickness of the existing bracket and the width of the mounting boss on the bottom of the alternator and noted them on the cardboard.

 

Using these dimensions I drafted a 3d model and printed it out to test fit it on the truck.

 

For clarity, here's sort of how the cardboard reference pieces sit in relation to the bracket, except that the one with the bend in it would actually go behind the rear fin:

 

I needed slightly more clearance between the alternator bottom and the outside corners of the horizontal web between the two fins, and I also decided I wanted a little more lateral stiffness between the fins, and why not extend the horizontal web to the rear corner and lengthen the radius on top of the fins?

I knew these changes wouldn't create any new interference, so for the next 3d print I also converted the model to a set of 3/16" thick plates that fit together with tabs and slots.

Assembled:

... and unassembled:

 

Before uploading the dxf files to sendcutsend I made one more change that wouldn't really be visible, but was important - for tabs and slots they recommended adding a 0.01" tolerance between the tabs and slots. In hindsight 0.005" probably would have worked, but the pieces fit together easily and I don't think they'll be difficult to hold together for welding.

Here's the 3d model and the flat version side by side:

 

I specified 3/16" hot rolled steel with no finishing.

Unboxing:

 

and pieces assembled

 

I've had the pieces here for a couple weeks now and other things are more pressing, but in the next day or two I may get around to welding it together, painting and installing it. When I do, I'll update this post with more pictures. Once I've verified my design really works I'll upload the dxf files here in case anyone else wants to try this.

 

The throttle cable mounting bracket was slightly different, as it needed several bends for stiffness and to accommodate hardware and pieces on different planes. Getting the initial dimensions was a lot more complicated, and I went through several 3d printed prototypes before I had one that fit and cleared everything it needed to. To get the dimensions of each flange correct, I used sendcutsend's very detailed and helpful articles on designing bends into a metal part, along with their bend calculator. Dashed lines in the dxf files automatically prompt sendcutsend's ordering system to ask for degrees and direction of bend for each line. The bend you're entering values for is highlighted in the 2d view, and the resulting bend is immediately shown in the 3d view as you enter the values.

Here's the prototype 3d model and the flattened version:

 

I ordered the parts in 0.06 thick 304 stainless steel. For some reason they sent me two of the main bracket, and I can't find any errors in either one. Only one sticker this time though...

 

For the rest of the throttle cable mounting bracket, see this post in my other thread:

 

 

Edited August 15, 2023 by hucklefish

[iceman510]

Nice work.

[Draker]

Those prices are pretty affordable. I had no idea. Very cool!

Nice work!

[mklotz70]

SendCutSend is awesome!  I have parts coming from them as I type.  I've used them for a couple of years now.  
 

Great write up and post!! Thank you. 🙂

 

[thisismatt]

You had me at Sour Patch Kids 😆. Another one to try is xometry...it's more of an aggregate site, though.