You can download fastener models from McMaster Carr. The only problem is they have modeled threads, which can really bog things down. I haven't gotten this far on the castings yet, so you're way ahead of me.
I have started downloading them which is nice because it retains the item number in the model. This will be good later when I need to purchase fasteners because I can just print the assembly bill of materials and not have to re-search the fasteners again.

Honestly, I think you will find that modeling the castings is not much of a problem. Once you figure out draft angles and the like, its pretty straight forward. The biggest trouble I have had so far in learning F360 is in the assembly of "joints". And really, the only one that gives me fits is the pin-and-slot joint. This is what you would use for a cam follower assembly, or sliding hinge of some sort. I used it for the cardan shaft according to Harold Hall's plans - which required some creative learning in F360 on my part.
 
I think what you might want to try for that joint is using a contact set. I agree, figuring out joints can be an exercise in frustration. I used the contact set to get a crank shaper model working, using a contact set between the slide block and the crank. As for modeling my Martin castings, I will probably model the castings as is by taking measurements, then model them as they are supposed to be machined, then do an assembly model.
 
As for modeling my Martin castings, I will probably model the castings as is by taking measurements, then model them as they are supposed to be machined, then do an assembly model.
That is exactly how I did the modeling. What you see are cast dimensions with corresponding machined faces and features from the Harold Hall series of articles as well as the features/dimensions I had to get creative with.
 
Yikes! I'm embarrassed that it has taken this long to get back to this project. Currently preparing to machine the base casting. In Harold Hall's article he spent a fair amount of time describing how he machined the awkward shaped and sized base casting. He ended up moving it several times and made compromises in the sequence of machining steps.

In thinking this through - HOW will I machine this on my little Atlas MF - I decided to machine this on an angle plate and use endmills. So, I started the fixture plate:

Base Casting Fixture.png

This model illustrates a 12" wide, 4-1/2" deep on the base by 10" high welded steel fixture plate. The plate is 3/8" thick 1018.

The fixture will be split into two pieces, 6" wide each - so that I can slide the fixtures into appropriate support areas and slide the base around correspondingly. This split feature will allow me to get clamps in the middle of the base and hold things securely. You can't see the split in the model.

Base Casting Fixture - Back View.png
Back view. The four straps are 3/8" x 1-1/2" x 8-1/2" high - spaced 4" in between straps.


Drilling Holes.jpg
Drilling holes in the 4-1/2" x 12" plate to bolt it to the table during machining. These will be used during machining when the fixture is in use as well. It should be obvious looking at this and considering my plan to make two fixtures that that I will cut this plate across the width to make two 6" wide bases. For now, we will machine it as one piece to keep everything aligned and true.

Next step is to bolt the plate up to the table and square it up. Then I milled a flat area where the vertical plate will be welded.
Milling flat for vertical plate.jpg

A couple of things to take notice of. The cutter is a 2" diameter, 3/8" wide side milling cutter. There is not a lot of clearance between the arbor spacers and the workpiece - limiting the travel on the table to either side of the arbor. No good. My solution was to grind down the tops of the socket head cap screws. You can also see if you look closely that there is some chatter/finish problems on the left side of the cut. I'm not to worried about the finish, as I'm going to be welding in this area anyway.

I didn't fully realize it at the time, but I was slowly stripping the table nut underneath using the full travel of this machine which explains what was going on with the finish to some extent. After I replaced the nut (which you can read about here) I flipped the part and milled some deeper grooves where I will weld in some 3/8" keys to the bottom of the fixture, this will allow me to drop the fixture(s) onto the table. Finish cleaned up nicely.

Prior to this part of the job, I cut the straps and verticals to length and deburred with a file. Here is a quick clip of the Miller's Falls saw cutting the verticals.

View attachment IMG_6849.MOV

















































The alignment of the saw is not great and it doesn't cut straight. So I had to clean up the ends and square them up on the mill.
IMG_6853.jpg

This was prior to the lead nut stripping and this was the first time I've put a couple of hours into the machine - I'm sure the power feed didn't help the lead nut either.

Anyway, more pics to come later!
 
Finished up the angle plates. Wrote it up as a proper project. See completed angle plates here....

Started layout and drilling holes for the base casting tonight.

Layout Photos

Base Casting.jpg

This casting is almost as old as me.

Layout 1.jpg

Laying out the first center-line of the casting. I clamped the straightedge to hold my line true.

Laying out the first centerline is not so critical for the mounting holes on that line. Those 3/8" holes will be consumed by a 5/8" wide slot for the lead screw that will move a cross slide on the gear hobber. However, the first center-line is a theoretical mark for other measurements on the base. In the next photo, you can see how I use a 1-2-3 block off the first center line to mark out 2". I slid another steel rule under the 1-2-3 block and snuck it 7/16" past the 2" block edge to find my location of the hole from the original center-line. Careful, patient clamping the rules and squares to the casting are the key to making this work.

Layout 2.jpg
Measuring off the center-line to mark 2-7/16" off the center mark.


Once I had the holes marked out on the right side of the casting, I moved to the other side of the center-line. There is a hole pattern on the little peninsula on the left side of the casting that holds an L-bracket secure in order to support the cardan shaft on the gear hobber. This time, I used the 1" edge of the 1-2-3 block and whatever the remaining fraction on the print was calling for.

While the cast surfaces are not precisely square, keep in mind that these are mounting holes for brackets that have either slots in the them or large clearance for mounting. The advantage of drilling these through the casting now is that I can use them for mounting holes on the angle plate fixture and mill the bottom of the casting without tooling interference. More on that in upcoming posts soon.

Layout 3.jpg
Laying out the rest of the mounting holes.


I then drilled the mounting holes...
Drilling Cast Iron Too Slow.jpg
See that fine cast iron dust? That means the cutting speed is too slow, or in this case about 500 rpm.

Drilling Cast Iron Just Right.jpg
See those heavier chips? That is getting closer to a better cutting speed. ~900RPM


The finished drilling operations:
Finished Drilling.jpg

The mounting holes on the feet will be used when milling the base in the as viewed position. The other holes will be used when I'm milling the bottom. The mounting holes on the feet are a little off-center. I will be opening this up to a slightly large size with an end-mill later.

Next up is milling the base flat and then the dovetails.
 
Last year I scrapped about 100 pounds of hobs from a machine shop I liquidated. Both gear and thread hobs. Tried to sell them cheap on CL and EBAY but only sold a few so they brought 4 cents per poundFlustered
Aaron
 
Super interesting project, I hope you continue it!
 
I still have a dozen or so of those hobs. You could have them for the price of shipping.
Aaron

Hi Aaron, will send you a PM. Definitely interested.


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