Machining

12 years at Rejent. Now moving.

Well, I’ve been here at Rejent on and off for the last 12 years. Now the company is moving to different digs and I figured I’d take some arguably unflattering pictures of the shop. Things are in disarray and thigs are a bit dirty as well.

Right now these things seem mundane but in 20 or 40 years there will be somebody, perhaps even myself who will enjoy looking at photos like these. Our new place will be in the old Precimax building and while it doesn’t have that much more room, it will be a fresh start and we can organize things with a pinch of pride.

Here’s to a good move!

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New Linear Gages are ready to go.

We’ve had these things in waiting for quite some time. I’ve designed them to be lighter, more accurate, less snaggy and a bit sleeker. They take the standard heads that I’ve made for the last 4 years and still move linearly so that you can put whatever kind of styli you want on them. The older ones used to snag due to the fact that there were two bearing being forced to cock over in certain circumstances.

A view of the working end of the gage

As things heat up in the world and the economy either booms or busts, hopefully we’ll be able sell some!

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Plumbo – A simple way to measure horizontal rotation

Over the years I’ve had issues with large parts and finding easy ways to lay them out angularly, especially on the ram EDM. During this time I’ve kind of tinkered in my head with an idea whereby you have a level of sorts stuck to the part and you simply rotate it and have a direct reading of rotation applied to the part. I have tried those digital levels but accelerometers don’t have the precision required to get within a few thou over, say 6 inches.

The prototype device as it is right now

It’s obviously very rough and uses a cheap Chinese 2000ppr encoder but it’s good enough for .045 degree increments. I would trust this thing for some larger layout and alignment work. That said, I have a nice US digital encoder on the way with 10000cpr (40000 ticks all the way around) so a resolution of .009 degrees. Some issues I’m having is with the mass. If the mass is too small it won’t overcome the friction of the bearings completely and if the mass is too large it swings for a long time making it a hassle to allow it to settle. I’d like to find a solution whereby I can add friction without adding stiction. Frankly the whole thing needs a good concept redevelopment but I believe it’ll be a handy tool in niche situations.

I’ll keep this updated as I go along.

Electronics
Machining
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The Gages are complete and ready to ship

After a bit of work and worry, the gages are ready for shipment and are as nice as I could hope for.

I’m quite proud of these, they’re repeatable and feel damned good in the hands.

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Some new DNMG boring heads I designed

Well, the new boring heads I designed came out well, especially after nitriding. Man! is that black finish ever nice! I’ve made many heads before but these turned out nicer than usual.

a forwards facing dnmg holder with a large offset

The whole order

The backwards dnmg holder

Well, things are getting busy, I’m sure there will be more to post soon, especially as our gages get done!

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The new gage!

Well, the prototype gage is here and it seems to work reasonably well. I’ve given it extra travel over the old ones and it seems to have really nice, smooth action.

Here are some pics

Now to make some styluses and start shipping these things around the world!

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Back at Rejent and back in the design chair

It been some time since I’ve updated this blog. While I have designed and made quite a few things, it’s been at the very bottom of my list to update this blog. Anyways, here are a few things I’ve worked on or am working on.

New RTJ gage

So, in an effort to simplify the manufacturing and generalize the usage of the gage I have redesigned it. With 3/4″ of travel it will allow for the use of almost any attachment along with the balls that typically fit something like this.

A rough early version of the new gage

Still will take some time to actually manufacture it but whatever.

A quick gage for a customer

These were commissioned from a customer for the quick checking of a particular size on a production job.

Nothing too spectacular there.

I’ve worked on a few other things such as the forklift safety system. This device was meant to be attached to the forklift and engage a horn when the forklift went to fast. It was completed but the company no longer required it.

Anyways, time to start some more interesting projects in the future.

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Inside an ALC-7701 Mitutoyo Scale Counter

I need to find out the pinout of a Mitutoyo Counter, well the encoders anyways. I wasn’t able to determine exactly which one was what but we’ll see.

When I do figure it out, I will post the pinout as best I know.

Electronics
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New Youtube Channel for a new time

I’ve decided to start a new Youtube channel simply because I feel as though adding my projects and the things that I like to a video channel will drive me in ways I hadn’t had before. Thus far, I have 0 subscribers (aside from myself) and I’m genuinely curious to see how well I can make a Youtube channel work out. I believe I have some interesting things to share and some boring but popular things to share as well and a new Youtube channel that explores all those things.

Here’s a link to the channel

https://www.youtube.com/channel/UCwxvlEKdkh9eV9qLXHBh3fw

Not the most graceful URL but I will get a better one once I get some subscribers and I’ve been around for a while. I will explore things that I do such as electronics, gaming, machining, photography and whatever else I come across.

Here’s a video detailing something mundane, my calculator collection.

So, feel free to look at my channel, subscribe and like a video or two. 🙂

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Diminutive, a small EDM prototype

For the last little bit I’ve been working on a small EDM prototype for use on large parts, pipe sections or for use in the field. While they do make and sell these things, the vast majority of them require the use of vibratory assistance, aren’t terribly accurate and are relatively low powered. I intend to make one that is accurate and could potentially be used as a ram EDM in a pinch. Also, I’d like it to be able to use copper and graphite electrodes so polarity reversal is necessary.

This is the linear drive of the small EDM. It has 8 inches of travel and is surprisingly rigid and play-free. I was going to use a gear motor on the top with a rotary encoder but since the loads are quite small a stepper should be OK, even at higher speeds.

This is the linear drive of the small EDM. It has 8 inches of travel and is surprisingly rigid and play-free. I was going to use a gear motor on the top with a rotary encoder but since the loads are quite small a stepper should be OK, even at higher speeds.

I’m currently trying to come up with ways to mount this guy on magnetic bases but also allow for small amounts of fine adjustment so that if there is a need for precision work, the unit can be dialed in. Right now the coupling is made of two pieces of steel. I’m going to replace one of them with nylon to reduce noise. I was going to use a spider coupler with rubber in between but I didn’t have one kicking around on the weekend when I was making it so I just made my own.

It's all made from 7075 aircraft aluminum. Pretty strong stuff. The movement was initially pretty stiff because the screw, which is just hot rolled, was a little bit out so I had to run it back and forth to wear in the brass acme nut. I may put two acme nuts into the travel block simply to take up play, as it stands though right now there is less tan .0003" of play, even with significant force applied.

It’s all made from 7075 aircraft aluminum. Pretty strong stuff. The movement was initially pretty stiff because the screw, which is just hot rolled, was a little bit out so I had to run it back and forth to wear in the brass acme nut. I may put two acme nuts into the travel block simply to take up play, as it stands though right now there is less tan .0003″ of play, even with significant force applied.

So next things next, the prototype electronics. Right now I’m simply going to use what I have laying around, so a TM1638 display, a cheap chinese stepper driver with a toshiba stepper driver and I opted for an Arduino to drive the motor. I will be making a full fledged PCB that will nicely fit in a box but I need to get the pulse generator and sensory circuits working first, then I can integrate them fully on to one PCB.

Just a rough testbed for the motion control and a simple interface. I would like this thing to be nice and easy to use.

Just a rough testbed for the motion control and a simple interface. I would like this thing to be nice and easy to use.

Well, anyways, I have quite a bit more work to do for this project. Even a single axis CNC can be a little more tricky since it’s doing more than simply positioning. A ram EDM is a dynamic machine that reacts to the sensory input to keep the cut running smoothly and with appropriate voltage and gap settings.

More later.

Electronics
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3D printing, some thoughts and a potential design

Some recent developments, whether they are fruitful or not, have got me thinking seriously about the design of 3D printers, their use and some of their current drawbacks.

Additive manufacturing has come a long way even in the last 15 years when it was just a novelty and not useful for much more than rough prototypes. While 3D printing will probably never supplant ‘subtractive’ methods such as turning and milling for most things, I believe it will be a real boon for strange, esoteric and one-off parts with limited mechanical demands.

This got me thinking about my own design and what I perceive to be some of the issues with current machines all the way up to commercial machines. A couple of those issues are of concern when making a upper-tier hobbyist grade machines for making prototype parts.

These two things are, the effects of gravity on the part when heated or produced, and the effects of uneven heating throughout the process of printing a given part. This will not only increase accuracy but reduce the need for support structures while printing.

Here is a rough pic of my idea for a 3D printer:

A rough mockup of the 3D printer

A rough mockup of the 3D printer

Having a heated suspension fluid eliminates the wow caused by uneven heating and the droop generated from gravity when the part is properly heated. By keeping the liquid level slightly lower than the workpiece you can still generate lattices without the fear of them filling in. The inflow and outflow should be computer controlled via electric pumps and valves, this way the fluid can remain hot without having to heat the whole enclosure. Draining from the bottom will partially help ensure that the cooler fluid is drained first. You could even add a filter to remove detritus.

For the fluid height sensor, I would probably try to tie it in with the nozzle height somehow without interfering with the work envelope. The level would need to be maintained very accurately in order to ensure maximum efficiency. For this sensor I would probably use my old design for a viscometer with the two Piezo discs, instead of measuring viscosity, I would just check for fluid contact, for this purpose it proved to be very accurate and resistant to fouling.

For the fluid, it should match the density of ABS fairly closely. Mineral oil or Propylene Glycol might be good candidates. The idea is to have a fluid that is non-toxic, non-flammable, somewhat viscous and chemically inert with plastics.

Some drawbacks

  • Fragile hollow objects with no holes (a ball) may become deformed due to fluid pressure. though this would require quite a bit of depth to achieve. Not to mention that the item would want to float.
  • Structure needs to be very rigid and acceleration and deceleration needs to be toned down as to not allow the fluid to slosh around which could shake the part loose during printing.
  • potentially messy with fluid being added to the mix.
  • mechanically more complicated and motion components need to be at least resistant to fluid being used.
  • Fluid would probably need to be changed with different materials. A fluid denser than the plastic being laid down may cause issues.
  • Stronger binding to the table is required especially with lattice heavy designs, floating will occur.

Anyways, that’s my idea, posted for posterity. Maybe someone will find it interesting or foolish.

Electronics
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VariGage moving along nicely

The ugly prototype of the Varigage Circuitry.

The ugly prototype of the Varigage Circuitry.

Well, things are proceeding, slowly but well. I’ve been busy with Christmas and general work and relaxing but it’s time to carry on with the device.

This prototype currently has the following features:

  • An Arduino Mega (will be replaced with a PIC)
  • HD44780 display module, may replace it with a nice flat transflective LCD
  • an ugly keypad
  • Input for quadrature from linear scale
  • Output to DC motor
  • Switching 12v to 5v supply
  • rs485 transciever for communication to the anvil

All of the parts are made but not entirely finished. Going to finish them soon. I was able to assemble them and the actuation is smooth as silk.

Anyways, gonna try to finish the mechanical soon so I can have the ungly prototype up and running. Hopefully I’ll be able to get a finished version ready for the oil show.

Electronics
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