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Curta Calculator Scale Replica
- Thread starter racer8412
- Start date
- Joined
- Feb 18, 2016
- Messages
- 451
Maybe I should use them to build a smaller lathe and mill...
I've been thinking about this myself.
I might have to cheat and use the CNC router for some bits.
I confess that I've been thinking the same thing. Especially for the setting shafts part# 10061 it's begging for a CNC machine.
Like you, I thought of making my own micro mill. Then when I saw the setting shaft I instantly thought that I could automate this using an Arduino and stepper motors to control the micro mill.
Then I just realized that I will have built a CNC machine.
Can't blame us. Who wants to sit there a mill a thousand dimples when an Arduino would do it with no complaints. Then I could go work on my '47 Chevy while the Arduino drills the perfectly spaced dimples.
- Joined
- Jan 9, 2013
- Messages
- 1,020
Yeah, but that takes all the fun out of it. 
I’m just too old to even think about taking on this complex of a project. I can see a LOT of time needed for this job. Kudos to any and every body who proceeds into this endeavor. Go get’em!
I’m just too old to even think about taking on this complex of a project. I can see a LOT of time needed for this job. Kudos to any and every body who proceeds into this endeavor. Go get’em!
- Joined
- Feb 18, 2016
- Messages
- 451
Yeah, but that takes all the fun out of it.
In that case when I get the setting shaft blanks cut to size I'll send them off to you for dimple drilling.
My donation to helping a grumpy old guy have some fun.
- Joined
- Feb 18, 2016
- Messages
- 451
We better quit. We're filling up Racer's project thread with silly chit-chat.
Just want to extend a gracious thanks to Chuck once again for sharing the beautiful photo of his awesome Curta.
Now everybody get back to work and find some dimples to drill or something.
Just want to extend a gracious thanks to Chuck once again for sharing the beautiful photo of his awesome Curta.
Now everybody get back to work and find some dimples to drill or something.
- Joined
- Feb 18, 2016
- Messages
- 451
Racer has agreed to accept my proposition to be one of his mentors. I live in Pennsylvania, USA and he lives in Flordia, USA. So I won't be able to mentor him live on how to correctly operate any machines he might use. Hopefully he can find someone in person to help with that end of things.
What I am going to offer are lessons on how he might take on a project like this. My plan is to just start making some parts. He'll need to make all the parts eventually so it really doesn't matter which parts we start with. I've chosen some of the more difficult parts to start with.
Racer is under no obligation to actually follow my mentoring suggestions. He can also continue to seek other mentors and input from anyone else at any time. In fact, I encourage that. All of my mentoring will be suggestions only. So Racer is free to decline my suggestions at any time.
My first suggestion is to hold off on buying any machines or tooling for now. There is much that will need to be done before any actual parts will be made anyway. As I see this project there will also be two main categories of parts.
1. Larger parts that can actually be made on standard size machine shop equipment.
2. Micro parts that are going to need special techniques to make.
My proposal to begin is to consider a single part. We going to consider making the transmission gears. These are "micro parts" that will be extremely difficult to make. In fact, I think that making these transmission gears can be a real test of whether or not it's worth moving forward on this project.
Here are the parts.
Part #10038 Transmission Gear I (20 required)
Part #10053 Transmission Gear II (22 required)
This is a total of 42 gears. I don't know about anyone else, but I'm not going to sit around trying to machine out 42 micro gears by hand.
Not only this, but if I build one of these things I want to tool up to be able to make more than one of them.
So my proposal (and that's all it is at this time) is to make punch and dies to punch these gears out from sheet brass. Making the punch and dies will be the machine shop work. We are still going to need to machine these gears. Potentially four times. Once for the punch profile, once for the die profile, and we'll probably need to do this twice to make separate punch and dies for the above two gears.
What's the difference between part 10038 and 10053? Thickness. Period. I double checked this by laying the two drawings over each other. The drawings are identical in terms of gear profile. The only difference is that Gear I is 0.5 mm thick, and Gear II is 0.6 mm thick.
Because of these different thicknesses we may need to make special punch and dies for each gear.
This is where Racer comes in.
His mission, if he should decide to accept, is to design the punch and dies to punch out these gears. We need to have them designed before we even start machining anything.
So here's my proposed homework for Racer:
Assignment:
Download and read this 16 page booklet
Stamping Basics
If you have a printer print out the 16 pages and put them in a binder. You'll find this information useful for future operations. This will be a good place to keep all your notes and calculations as well.
Detailed Study:
Read on pages 2 - 3 the sections marked:
Punch Press
Simple Die
Compound Die
(You will need to design a compound die for this)
Read and take note of all the different types of Punch Operations
Page 7 - Stamping Terminology.
(for now we will only be using a "perforating" operation)
Read also on page 7 - Perforating
On page 8 copy the Perforating Pressure Formula information.
(You'll need this to make your calculations)
On page 14 read
Shear Angles
(this will just give you some understanding of the different types of cutting edges a punch can have. You don't need to understand shear angles at this time. Just be aware that they are important)
When you're done with this we can move forward to the next stage which will be a second homework lesson concerning the design of punch and dies. You'll need to calculate punching pressures, and required clearances, etc.
Let me know when you have completed the above homework and I'll give you the next homework lesson.
Note to Racer: This all assumes, of course, that you agree with my proposal to punch out these gears. If you have another manufacturing process in mind, then you'll need another mentor.
Note to other Machinists: If you have a better idea of how to make these gears by all means chime in. I am in no way suggesting that my ideas are the only way to go, nor the best way forward. All I know is that I'm not about to sit down and try to machine out 43 micro gears individually. So this is my proposed solution. And just for the record I did think about cutting all the gears at once on a shaft, and then parting them off individually. The problem with that is the key in the center hole. You can't just drill a round hole through the stock. You need that triangular key. So it has already been suggested to me that after machining the rod and parting off the individual gears, I would still need to punch out the center hole. So why bother with double work? Why not just punch out the whole gear in one fell swoop and be done with it? The gears can then be deburred in a tumbler with the correct grit medium. That's my proposal. If you have a better idea that isn't CNC or Laser Cutting, by all means offer it up.
Second note to Racer: Don't worry about machining. You'll need to machine the punch and dies. So you'll be machining these micro parts. You'll have ample opportunity to be machining all sorts of things as a tool and die maker.
What I am going to offer are lessons on how he might take on a project like this. My plan is to just start making some parts. He'll need to make all the parts eventually so it really doesn't matter which parts we start with. I've chosen some of the more difficult parts to start with.
Racer is under no obligation to actually follow my mentoring suggestions. He can also continue to seek other mentors and input from anyone else at any time. In fact, I encourage that. All of my mentoring will be suggestions only. So Racer is free to decline my suggestions at any time.
My first suggestion is to hold off on buying any machines or tooling for now. There is much that will need to be done before any actual parts will be made anyway. As I see this project there will also be two main categories of parts.
1. Larger parts that can actually be made on standard size machine shop equipment.
2. Micro parts that are going to need special techniques to make.
My proposal to begin is to consider a single part. We going to consider making the transmission gears. These are "micro parts" that will be extremely difficult to make. In fact, I think that making these transmission gears can be a real test of whether or not it's worth moving forward on this project.
Here are the parts.
Part #10038 Transmission Gear I (20 required)
Part #10053 Transmission Gear II (22 required)
This is a total of 42 gears. I don't know about anyone else, but I'm not going to sit around trying to machine out 42 micro gears by hand.
Not only this, but if I build one of these things I want to tool up to be able to make more than one of them.
So my proposal (and that's all it is at this time) is to make punch and dies to punch these gears out from sheet brass. Making the punch and dies will be the machine shop work. We are still going to need to machine these gears. Potentially four times. Once for the punch profile, once for the die profile, and we'll probably need to do this twice to make separate punch and dies for the above two gears.
What's the difference between part 10038 and 10053? Thickness. Period. I double checked this by laying the two drawings over each other. The drawings are identical in terms of gear profile. The only difference is that Gear I is 0.5 mm thick, and Gear II is 0.6 mm thick.
Because of these different thicknesses we may need to make special punch and dies for each gear.
This is where Racer comes in.
His mission, if he should decide to accept, is to design the punch and dies to punch out these gears. We need to have them designed before we even start machining anything.
So here's my proposed homework for Racer:
Assignment:
Download and read this 16 page booklet
Stamping Basics
If you have a printer print out the 16 pages and put them in a binder. You'll find this information useful for future operations. This will be a good place to keep all your notes and calculations as well.
Detailed Study:
Read on pages 2 - 3 the sections marked:
Punch Press
Simple Die
Compound Die
(You will need to design a compound die for this)
Read and take note of all the different types of Punch Operations
Page 7 - Stamping Terminology.
(for now we will only be using a "perforating" operation)
Read also on page 7 - Perforating
On page 8 copy the Perforating Pressure Formula information.
(You'll need this to make your calculations)
On page 14 read
Shear Angles
(this will just give you some understanding of the different types of cutting edges a punch can have. You don't need to understand shear angles at this time. Just be aware that they are important)
When you're done with this we can move forward to the next stage which will be a second homework lesson concerning the design of punch and dies. You'll need to calculate punching pressures, and required clearances, etc.
Let me know when you have completed the above homework and I'll give you the next homework lesson.
Note to Racer: This all assumes, of course, that you agree with my proposal to punch out these gears. If you have another manufacturing process in mind, then you'll need another mentor.
Note to other Machinists: If you have a better idea of how to make these gears by all means chime in. I am in no way suggesting that my ideas are the only way to go, nor the best way forward. All I know is that I'm not about to sit down and try to machine out 43 micro gears individually. So this is my proposed solution. And just for the record I did think about cutting all the gears at once on a shaft, and then parting them off individually. The problem with that is the key in the center hole. You can't just drill a round hole through the stock. You need that triangular key. So it has already been suggested to me that after machining the rod and parting off the individual gears, I would still need to punch out the center hole. So why bother with double work? Why not just punch out the whole gear in one fell swoop and be done with it? The gears can then be deburred in a tumbler with the correct grit medium. That's my proposal. If you have a better idea that isn't CNC or Laser Cutting, by all means offer it up.
Second note to Racer: Don't worry about machining. You'll need to machine the punch and dies. So you'll be machining these micro parts. You'll have ample opportunity to be machining all sorts of things as a tool and die maker.
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