Any machinists in the house?

[nobbie48]

I've been meaning to post a drawing with sizes.. Now I've gone down the rabbit hole of learning how to use Fusion 360 to create those diagrams. Overkill, for sure for this purpose, but I like learning new things.

I also had the crazy idea of using Delrin to make these fittings. Cheap (I think, but maybe not if I can source some cheaper steel?), light, easy to source, easy to machine. I also went down the rabbit hole of reading about the mechanical properties of various materials. I already knew that Delrin not nearly as strong as steel, and now I know things like its shear modulus is an order or 2 of magnitude less than steel - but maybe it is strong enough for this purpose. Crazy, right?

@Brian P and @GreyGhost You're right about my diameters. I think it's more like 1-1/4" in the widest aspect of the fittings - should save me some costs.

Also - I found out why I was having trouble cutting the brass. Something is wrong with the cross slide so as soon as it encountered even a tiny bit of pressure it would refuse to move much. I need to figure out what the problem might be, but fortunately I had another Sherline lathe that didn't have the problem so I just jumped to that.

So many rabbit holes! Every project I undertake is like that - I wonder what that says about me.

My opinions:

Brass can be weird to drill and turn. It tends to grab the cutter and needs a different rake on the cutter.

Those mini lathes have a tendency to let chips jam the feed rack and pinion. I'm working a deflector brush to minimize the situation on mine.

Plastic (Delrin) is harder to find and not cheap compared to more common materials. It's great for bearings but there's a reason they don't make car chassis out of it. Sometimes when the materials and time are on hand, I unnecessarily make things out of polished brass and stainless so they look pretty.

A lot of time I make a part out of mild steel (simple, strong and cheap) then I hit it with gun blue and a wipe of oil. It wouldn't work for a marine environment but your call.

I knew a guy building a 35 foot sailboat and he needed a sink for the galley. A standard $50 bar sink would have worked but they are 304 so he paid a sink company in Midland $400 to punch one out in 316. Then he changed the layout of the galley and it didn't fit.

 

[Brian P]

I knew a guy building a 35 foot sailboat and he needed a sink for the galley. A standard $50 bar sink would have worked but they are 304 so he paid a sink company in Midland $400 to punch one out in 316. Then he changed the layout of the galley and it didn't fit.

Design changes are a headache.

In the perfect world, the concept drawings get fleshed out and design frozen before detail drawings are done, and those get done before anyone cuts metal.

In the real world, people change their minds late in the game, errors and oversights are inevitable and don't get discovered until late enough that stuff has to get redesigned to fix them, designs have to be put out there while unknowns remain unresolved, real world testing finds that a process doesn't work or isn't capable of meeting specs or has some unforeseen problem, etc. I have decades of stories...

Try not to cut metal until you're sure what you want.

 

[NuggyBuggy]

I had a chance to meet @85K100 today- he showed me around his garage and very generously gave me some cutting tools that will hopefully fit my tool posts, and gave me a lot of advice.

We talked for a few hours about machining, bikes, and a bunch of other things.

Thank you @85K100 - it was a pleasure - let me know if you need help dropping that tree!

 

[85K100]

Nice to meet you Mr. Nuggy! Glad to help. Pass it on... :^)

 

[NuggyBuggy]

I bought 16" of 2" diameter mild steel from "Mr Metal" near Sherway. Learned a few things.

1) Cutting steel without a good vise is hard.
2) Cutting steel with a hacksaw blade is hard.
3) Cutting steel with a hacksaw blade oriented the wrong way is even harder.


I was very disappointed the only 18tpi hacksaw blades I could find were Mastercraft ones. Not sure how much the blades factored into the difficulty I had. I was hoping to buy Lenox blades but I could only find them in sets that had blades I didn't want. Home Depot didn't even have bimetal blades.

I might just take it up north and put a bimetal blade on my Sawzall and go to town. Or put a cutoff wheel on my angle grinder.

 

[GreyGhost]

I bought 16" of 2" diameter mild steel from "Mr Metal" near Sherway. Learned a few things.

1) Cutting steel without a good vise is hard.
2) Cutting steel with a hacksaw blade is hard.
3) Cutting steel with a hacksaw blade oriented the wrong way is even harder.


I was very disappointed the only 18tpi hacksaw blades I could find were Mastercraft ones. Not sure how much the blades factored into the difficulty I had. I was hoping to buy Lenox blades but I could only find them in sets that had blades I didn't want. Home Depot didn't even have bimetal blades.

I might just take it up north and put a bimetal blade on my Sawzall and go to town. Or put a cutoff wheel on my angle grinder.

That's a lot of steel for a handheld hacksaw to get through. A bandsaw is a much nicer tool to use (both easier and faster). I only buy bimetal blades. Life's too short for crappy blades. Try IHL, atlas, kbc, etc for a better selection of good tools.

I assume you can't fit it through the headstock and you need smaller pieces to work with?

 

[NuggyBuggy]

That's a lot of steel for a handheld hacksaw to get through. A bandsaw is a much nicer tool to use (both easier and faster). I only buy bimetal blades. Life's too short for crappy blades. Try IHL, atlas, kbc, etc for a better selection of good tools.

I assume you can't fit it through the headstock and you need smaller pieces to work with?

I just can't afford the space for a metal chop saw or a bandsaw.

The bar I have is pretty heavy. I have just enough distance between centers to handle the length, but I figured it would be much easier to work with smaller pieces. I’m not sure how well that little motor could spin that weight.

 

[GreyGhost]

I just can't afford the space for a metal chop saw or a bandsaw.

The bar I have is pretty heavy. I have just enough distance between centers to handle the length, but I figured it would be much easier to work with smaller pieces. I’m not sure how well that little motor could spin that weight.

Every time you cut off a piece you waste a bunch. Your cut won't be straight and ideally you don't want to be clamping on finished surfaces. If you want to cut off pieces faster and easier, chuck it in the lathe, center drill, use a center to support the free end, turn on lathe spinning slowly towards you, use hack saw. Voila, you've converted a hacksaw into something similar to a bandsaw with lots of material.moving past the teeth before you reset. It's easier/better if you can start (or do the whole thing) with a parting tool but I don't know if you have one.

Rotational inertia of a 2" bar along its length isn't horrendous. I'd try making parts on the end of the bar before I cut it up. Make sure you use a center.

 

[nobbie48]

How many cuts do you have to make in the 16" bar?

You can get a straighter cut if you tighten pipe clamps around the bar as guides.

To accurately drill a centre hole for the dead end of the lathe, the end being drilled should be near the chuck. If the lathe is small the bulk of the 16" bar won't fit through the shaft. A steady rest would help in that case.

My Milwaukee 18-volt metal cutting circular saw does a nice job on thinner stuff but 2" could be a problem.

I'd use my abrasive cut off saw, smell, noise and sparks be damned.

And sometimes you just have to suffer for a good cause.

 

[NuggyBuggy]

I’m planning on making some pieces which will probably range from 2-4”, so I expect maybe a half dozen cuts or so? These are trial runs while I learn to machine metal, and while I experiment with dimensions.

The largest diameter I need to get to is about 1-2/3”- originally I thought they would end up closer to 1-1/4” but the swingarm pivot recesses on my bike are much wider than the bike whose fittings I do have.

For accuracy of the location of the hole for the center drill - I’m wondering if it really matters in my case. I understood that if you turn stock in a lathe, what you get must be concentric with the lathe. Since the stock I have is significantly wider than my target dimension, even if the initial hole I drill is off center, won’t I get a piece that is perfectly centred around my hole?

The problem I see is that I can’t just turn the whole rod down to my largest dimensions, then rely on the above each time I work on another piece, since I will be compounding my errors each time I drill a center hole that is not on centre.

That being said, I do know that it’s ideal to have as much of the piece held in the chuck as possible, which was one reason I was trying to cut down the rod. Since this is all experimentation, I am not really worried about waste.

One last thing: ita pretty clear my ability to measure the recess of my swingarm pivots - especially the internal contours -is pretty poor. So I expect this will require some trial and error.

Since I am learning some CAD software (Fusion 360) as part of this rabbit hole, I hit on the idea of 3-printing pieces as I home in on the measurements. I like this idea since it would minimize mess (how do home machinists keep their space clean??) and won’t require me repeatedly sourcing metal (has been challenging for me to do inexpensively).

 

[GreyGhost]

A set of bore gauges are cheap and make you life a lot easier. Them plus calipers gets you most of the dimensions close enough for this project. If you have tapers, angle gauges could be helpful but not necessary.

As for 3d printing samples, start by printing cross section profiles. They will be much faster and use less filament (yould could even just print 1/4" outline with the entire centre empty). The profile should fit nicely in the hole and you can see where it doesn't fit properly. You can also make quick subtractions with a file to make a positive shape that is easier to measure. If you really want to confirm before steel, after you get the cross section right, revolve it to make your cone and print one as a final check/reference while working on steel.

 

[85K100]

Coincidentally, I demonstrated the use of a bore gauge during his visit.

 

[timtune]

One last thing: ita pretty clear my ability to measure the recess of my swingarm pivots - especially the internal contours -is pretty poor. So I expect this will require some trial and error.

Would it be possible to to use some stiff card and make paper templates that fit the internal contours?
I would think based on what you're doing you don't need much more than accuracy to decimal points. 10 thou vs 1 or 2.
With scissor s and paper you should be able to get within 10 thou.

 

[NuggyBuggy]

I did use some inside calipers to take dimensions. I stuck toothpicks into the recesses and marked them to get estimates of depths.

I also tried pushing play dough into the recess to make a mold to take dimensions from. But after pulling them out the molds weren't very crisp and didn't allow me to take measurements that were much better.

I agree that I probably don't need to be super accurate - maybe just roughly in the neighbourhood would be good enough. I wouldn't be surprised if getting close-to-right-size sockets might be usable as the starting point.

But there's a part of me that would like to learn how to do somewhat accurate work. I know the tools I have are capable of doing quite accurate work.

I have a lot of side projects and yard work that take my attention and so I tend to be a bit of a squirrel when I'm where my bikes are - but this is one of a smaller set of projects I can take on when i am in the city.

Right now, I think I'm going to focus on learning how to create models in Fusion 360, with the idea that I could use 3-d printing to really home in on the right dimensions before machining. @GreyGhost gave a lot of good ideas to make this more efficient.

 

[Mad Mike]

I bought 16" of 2" diameter mild steel from "Mr Metal" near Sherway. Learned a few things.

1) Cutting steel without a good vise is hard.
2) Cutting steel with a hacksaw blade is hard.
3) Cutting steel with a hacksaw blade oriented the wrong way is even harder.


I was very disappointed the only 18tpi hacksaw blades I could find were Mastercraft ones. Not sure how much the blades factored into the difficulty I had. I was hoping to buy Lenox blades but I could only find them in sets that had blades I didn't want. Home Depot didn't even have bimetal blades.

I might just take it up north and put a bimetal blade on my Sawzall and go to town. Or put a cutoff wheel on my angle grinder.

In metalwork you'll find an angle grinder is your best friend.

Use it with a cutoff wheel to cut your plugs.

 

[85K100]

You could try making a mock up out of wood to test for fit.

 

[Mad Mike]

I’m planning on making some pieces which will probably range from 2-4”, so I expect maybe a half dozen cuts or so? These are trial runs while I learn to machine metal, and while I experiment with dimensions.

The largest diameter I need to get to is about 1-2/3”- originally I thought they would end up closer to 1-1/4” but the swingarm pivot recesses on my bike are much wider than the bike whose fittings I do have.

For accuracy of the location of the hole for the center drill - I’m wondering if it really matters in my case. I understood that if you turn stock in a lathe, what you get must be concentric with the lathe. Since the stock I have is significantly wider than my target dimension, even if the initial hole I drill is off center, won’t I get a piece that is perfectly centred around my hole?

Mount the stock in the chuck and a drill chuck in the tail stock. Use the lathe to drill the centerhole - it will be near perfect.

The problem I see is that I can’t just turn the whole rod down to my largest dimensions, then rely on the above each time I work on another piece, since I will be compounding my errors each time I drill a center hole that is not on centre.

That being said, I do know that it’s ideal to have as much of the piece held in the chuck as possible, which was one reason I was trying to cut down the rod. Since this is all experimentation, I am not really worried about waste.

One last thing: ita pretty clear my ability to measure the recess of my swingarm pivots - especially the internal contours -is pretty poor. So I expect this will require some trial and error.

You need a simple $10 vernier caliper to do this. They measure OD, ID and depth

Since I am learning some CAD software (Fusion 360) as part of this rabbit hole, I hit on the idea of 3-printing pieces as I home in on the measurements. I like this idea since it would minimize mess (how do home machinists keep their space clean??) and won’t require me repeatedly sourcing metal (has been challenging for me to do inexpensively).

 

[timtune]

Mount the stock in the chuck and a drill chuck in the tail stock. Use the lathe to drill the centerhole - it will be near perfect.

You need a simple $10 vernier caliper to do this. They measure OD, ID and depth

View attachment 74996

One of the most used tools in my shop.

 

[nobbie48]

In metalwork you'll find an angle grinder is your best friend.

Use it with a cutoff wheel to cut your plugs.

I have a half dozen of the things and consider them inventions of the devil, the most dangerous tool in the shop. The exception being the battery one with a flap disk.

For cutting steel I use a purpose made Makita chop saw. Cold cut saws are nice, but I wouldn't use it enough to justify the price.

 

[Mad Mike]

I have a half dozen of the things and consider them inventions of the devil, the most dangerous tool in the shop. The exception being the battery one with a flap disk.

For cutting steel I use a purpose made Makita chop saw. Cold cut saws are nice, but I wouldn't use it enough to justify the price.

They can be dangerous - I have the scars to prove that. If you use them correctly (guard on, safety glasses, 2 hands on the grinder, work piece secured) they are no worse than any spinning power tool.

If you’re cutting down a 1/2 bolt with grinder in one hand and bolt in the other… YMMV.