360* Rotating Back Blade Project

[3RRL]

Renze,
I agree with you that if it does the job it's fine for me. I am a Dutchman too and appreciate your efficient way of thinking. You may have seen some of the other stuff I've made for my own tractor and I use that approach a lot.
But this project is a return favor for one that Larry did for me already. I place a lot of value in our friendship and this is exactly what he wanted. I promised him I'd help him with the machining aspect of it so he could finish his project he's been dreaming about for a long time. I am retired so this is fun for me and I appreciate the opportunity to help someone else for a change, especially after what Larry has done for me already.

Some of the details about machining are just to get my post count up. What's really fun that it's all being done on my stone age equipment in my garage shop, the old school way before CNC, EDM, Wire machines and automated equipment took over. It might take some guys back a few years to when they first started out in the trade like Scotty for example.
I'm glad you are enjoying Larry's thread. His home made project will be pretty cool when it's finished.

 

[Renze]

I know what CNC means, but what's EDM ???
I did get all that stuff at school, though we started on the old Deckel mills like mentioned in this thread before.

What can i expect to pay for an old but usable mill and lathe ? Lately i decided that i have exceeded the age to spend all my hard earned money in the pub and the dancing, but i'm young enough to be able to invest in workshop toys (because i dont have a wife and kids that need money too...)

I'm not sure what the best investment will be long term, but for now i'm happy buying metal working toys.

 

[montejw]

I know what CNC means, but what's EDM ???
I did get all that stuff at school, though we started on the old Deckel mills like mentioned in this thread before.

What can i expect to pay for an old but usable mill and lathe ? Lately i decided that i have exceeded the age to spend all my hard earned money in the pub and the dancing, but i'm young enough to be able to invest in workshop toys (because i dont have a wife and kids that need money too...)

I'm not sure what the best investment will be long term, but for now i'm happy buying metal working toys.

I'm a wannabee machinist. EDM is Electrical Discharge Machining. Basically you create an electrical circuit with your part and a shaped electrode. You point the electrode at your part and the electricity sparking between the electrode and your part eats away at the part. There's way more to it than that, but it's sparks for the most part.

More simply, have you every jumped a car starter, or directly across the battery? What happened? You probably lost a little bit of the tool you used to make the jump. EDM in action.

Monte

 

[Renze]

Hmm In Holland, literally translated, EDM is just spark machining. Well i think its only used to make microscopic holes in diesel fuel injectors and similar micro size, mega precision work.

 

[montejw]

Hmm In Holland, literally translated, EDM is just spark machining. Well i think its only used to make microscopic holes in diesel fuel injectors and similar micro size, mega precision work.

I don't think that's all it's used for. One example is machining very hard metals, tool making, etc.

Monte

 

[3RRL]

Before finishing the bores to the final size, I had to measure them accurately. Here are a couple ways that I use since I don't have a dial bore gage. Most of my stuff is stone age but still accurate.
This first one is checking with the dial calipers across the diameter, but that may not be the best way to do it. But if you are doing it without forcing, you can get a very good measurement that way. Double check a couple of readings with them and be sure the jaws are square to the bore.



Next way is a little more accurate. These are telescoping gages. They are spring loaded outwards and you move them around so they are expanded to the fullest inside the bore, but tilted a little so one end is deeper in the bore than the other and they are expanded larger than the bore. But on a shallow bore like this it's harder to do. Then you lock them and drag them out square to the bore so they collapse to the real bore diameter. With them locked, they stay in that position/dimension. Measure over the rounded tips with a micrometer and repeat to verify it is a good reading.



The last method and most accurate (that I have) is using gage blocks and gage pins. They are marked as to what size they are exactly and you fit them into the bore until you get a "snug" fit. Add them up and that's what the measurement is. The gage pins I have are a "minus" set so they are .0002" (2 ten thousands of an inch) under the size written on them. So I generally mic over the stack to verify the dimension. You can get excellent readings this way.

 

[3RRL]

For reference, here is a set of gage pins. I have sets from .010" to .060" diameter, .061" to .250"diameter, and .251" to .500" diameter sets of these. There are large sets too, but as you saw above, I combine them with gage blocks or use more than one pin to check larger bores.



This is an 81 piece set of gage blocks that are accurate to .000050" (fifty millionth of an inch). They are certified ... or were and can trace the certs back to Bureau of National Standards. You can stack them together to measure larger pockets or whatever.

 

[3RRL]

I flipped the plate over so I could start on the oil seal pockets. The first one went pretty quick and I made it a .005" press fit. I measured Ø2.570" and I made the pocket Ø2.565". I also made a tool to seat the oil seals.
Here is the first one.



Well that was easy so I did the second one but guess what? That oil seal was .005" smaller than the first one. So my pocket was a perfect slip fit instead of a press fit. DANG, should have measured them both!!! After all, I did that with those collars that were not the same diameter. I better fix it or Larry will have a cow.
So I TIG welded a small bead all along the inside of the bore and reset it up to re-machine again.



What a pain!!! But after re cutting it, the bead came out perfect with .005" press fit. I used 420SS rod so the cut would not be super hard. I stayed off the finished bottom and also avoided welding over the top edge. Had to stay between them on the .230" tall wall. Welding along the ID was hard job! But now he won't even know the difference.



Here they are both all pressed in and ready to go. That made me happy again.



BTW, I figure between all the rotary table pockets, roughing and finishing passes, I will make at least 80 to 100 passes or turns of the rotary table. You do the math on how many cranks that is ... just on the RT alone, not including the mill or lathe or surface grinder work. Gee thanks Larry. ;D

 

[3RRL]

Next for my vacation project was to turn the collars to accept the thrust bearing races. Larry has 2 sizes and the larger 2" bearings did not fit the collars like the smaller 1-½" ones. Great.
So I set up in the lathe and indicated the pieces in. My 3-jaw chuck is not that great and decided not to use soft jaws, but rather shimming the collars if needed.
Here is some .001" shim stock I will use to get the collars dead center.



Since the collars are located by their OD, I indicated in the OD and didn't worry about the ID since I would cut that anyway and it would run true to the OD. I could not bear checking to see if their OD ran concentric to their ID anyway. That would drive me nuts if it didn't.



Not only does the OD have to run true in the chuck, but the face has to be flat too. So I had to indicate the face for flatness so the new bore is square to the face.



That's how you do that before you start cutting anything. I got the face dead flat and the OD to run within .001" total indicator reading meaning the MOSt it would be out of center is .0005" (five ten thousands of an inch). Not the greatest, but plenty good enough for these big slow turning gears. Another thing to remember is that one of these collars is held in the top lid. There will be a slight amount of clearance (.001") in the way it (the lid) fits the box anyway, so Larry can take it off and on.

 

[3RRL]

Once I got everything indicated properly, I started boring out the collars. Turns out they are hardened!!! So I used an old 1" solid carbide end mill and put it in a boring bar holder. Now the tool and holder was short and stubby for maximum rigidity. My old AcraTurn lathe ate it up and never missed a beat.
Here I am checking the bore for size.



I wanted a very good fit here and the lathe repeated nicely. I mean when I dialed another .0005" it cut that exactly. I love my lathe.
Here is the bearing race tapped into the collar bore....Another perfect job done in record breaking time. :