Linear stepper motors

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o_lampe
You should've kept the forcer until you've made a decent working rail. Now you have to start with narda and it will be hard to find out which part is OK or not.

Or was it so cheap, because it was sold as defect?

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klcjr89

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o_lampe
You should've kept the forcer until you've made a decent working rail. Now you have to start with narda and it will be hard to find out which part is OK or not.

Or was it so cheap, because it was sold as defect?

Cheap because defective. They aren’t hard to come by, and I’m still devising the best way to cut slots in the linear rail effectively using relatively easy to get tools.

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dc42

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klcjr89

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o_lampe
You should've kept the forcer until you've made a decent working rail. Now you have to start with narda and it will be hard to find out which part is OK or not.

Or was it so cheap, because it was sold as defect?

Cheap because defective. They aren’t hard to come by, and I’m still devising the best way to cut slots in the linear rail effectively using relatively easy to get tools.

Did you see my note about using laminated iron parts, to avoid big eddy current losses at high speeds?

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Grain-oriented electrical steel usually has a silicon level of 3% (Si:11Fe). It is processed in such a way that the optimal properties are developed in the rolling direction, due to a tight control (proposed by Norman P. Goss) of the crystal orientation relative to the sheet. The magnetic flux density is increased by 30% in the coil rolling direction, although its magnetic saturation is decreased by 5%. It is used for the cores of power and distribution transformers, cold-rolled grain-oriented steel is often abbreviated to CRGO.

CRGO is usually supplied by the producing mills in coil form and has to be cut into "laminations", which are then used to form a transformer core, which is an integral part of any transformer. Grain-oriented steel is used in large power and distribution transformers and in certain audio output transformers.[8]

CRNGO is less expensive than CRGO. It is used when cost is more important than efficiency and for applications where the direction of magnetic flux is not constant, as in electric motors and generators with moving parts. It can be used when there is insufficient space to orient components to take advantage of the directional properties of grain-oriented electrical steel.

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dc42
Given that the magnetic circuit will include a significant airgap, I doubt that it will make much difference. But I don't consider myself to be an expert on this matter.

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The forcer armature must be made of
silicon steel laminated sheets, having high saturation level and low
specific losses.

The flux density in the mover’s poles ( B p ) is limited only
by the saturation of the teeth. Excessive saturation absorbs too
much of the excitation MMF or gives rise to extreme heating due to
core losses. As the tooth width is approximately half of the tooth
pitch, the maximum pole flux density can not be much above the
half of the saturation flux density of the steel lamination.

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691175002
The most difficult part of the project will likely be finding appropriate rail and cutting grooves in it. I think you might end up needing one of the back-mounting variations (ex: [www.automation-overstock.com] ) because hole counterbores in standard rail might cause issues.

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o_lampe

I see skipped steps, everytime the forcer crosses the mounting holes. If you want to make it more consistent, you'd have to cut the sides of the rails and build the forcer in a C-shape.

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691175002
The holes will certainly reduce motor force, but that doesn't guarantee it will lose steps.

The H2W 0602 forcer requires 18mm wide teeth to generate 10N of force. I assume that their rail is appropriately sized, so we can assume that a 15mm wide rail can generate ~8N and the 9mm sections around the holes will do ~5N.

Of course a hole only affects one half of the forcer, and only reaches its full diameter for a few teeth, so its possible you will get more than 5N of force over a hole. The question is then whether torque ripple (or microstep non-linearity from saturation) produces visible print artifacts.

I think its plausible enough to be worth trying, especially if you can find wire EDM cheaply enough. That process tends to vary significantly in cost since typical EDM machines are designed to hold tolerances probably two orders of magnitude more precise than you need.

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691175002
The holes will certainly reduce motor force, but that doesn't guarantee it will lose steps.

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o_lampe
I'm sure robotdigg would be able to send you rails without too many mounting holes, if you ask.

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Trakyan
This may be a stupid idea, but instead of cutting slots, has anyone considered laminating thin sheets of steel/iron and some other material into a stack, then taking a slice of that?
As long as your sheet material is the right thickness, and to relatively good tolerance it should give you a strip with alternating magnetic and non magnetic surfaces. Again, could be a stupid idea, just throwing it out there. Dunno what tools you guys have, but nothing I have could cut precisely spaced slots in a rail, but laminating it and milling/cutting the excess to get a rail shape seems doable with basic tools.

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klcjr89

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Trakyan
This may be a stupid idea, but instead of cutting slots, has anyone considered laminating thin sheets of steel/iron and some other material into a stack, then taking a slice of that?
As long as your sheet material is the right thickness, and to relatively good tolerance it should give you a strip with alternating magnetic and non magnetic surfaces. Again, could be a stupid idea, just throwing it out there. Dunno what tools you guys have, but nothing I have could cut precisely spaced slots in a rail, but laminating it and milling/cutting the excess to get a rail shape seems doable with basic tools.

You will need something to hold all of the laminations together, and then would need to surface grind the surfaces. The goal is to mass produce these, so the equipment doesn't put me off for getting the prototypes made.

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MKSA
I wonder how you could mass produce these and be competitive with the many current mfgs, making these for decades and in various form: flat, two axes (X Y) or even in round form (the guide is round, the coils around it ). And there is a lot more than just cut slots in a bar which in fact is the easiest part if you have the machine tools.

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klcjr89
Should this thread be moved here? [forums.reprap.org]

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klcjr89

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Trakyan
This may be a stupid idea, but instead of cutting slots, has anyone considered laminating thin sheets of steel/iron and some other material into a stack, then taking a slice of that?
As long as your sheet material is the right thickness, and to relatively good tolerance it should give you a strip with alternating magnetic and non magnetic surfaces. Again, could be a stupid idea, just throwing it out there. Dunno what tools you guys have, but nothing I have could cut precisely spaced slots in a rail, but laminating it and milling/cutting the excess to get a rail shape seems doable with basic tools.

You will need something to hold all of the laminations together, and then would need to surface grind the surfaces. The goal is to mass produce these, so the equipment doesn't put me off for getting the prototypes made.

maxresdefault.jpg

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o_lampe
Press fit plugs might not survive the cutting procedure, so why not cut a thread in the mounting hole and screw the plugs in?