New DIY UMT design

I've modified my Milestag UMT design to correct a problem with the original.

The problem is that the muzzle flash LED is wired in parallel with the infra red LED:

This is an issue because the forward voltage of the IR emitter is 1.35V, and that of the muzzle flash LED is 2.1V. This results in the muzzle flash illuminating far below its potential.

My new design has two outputs, one for the IR LED, and one for the muzzle flash LED. Both are driven from the same MOSFET but the current limit resistor is dedicated to the IR LED:

The muzzle flash LED will require its own current limiting resistor, but this matches the original Milestag design.

Here's the PCB, it will be available as a kit at TAGBITS in a few weeks:

Bugdet Milestag- Continued

I've been continuing the development of my budget Milestag gun kit. This is designed to have a single sensor on the gun body to reduce the cost of the unit. Initially I've concentrated on the sensor electronics. I've created a kit to make a Milestag sensor:

Here it assembled. Surface mount components are a lot easier to solder than through hole:

This needs to be mounted in a sensor housing that can be fitted to the breech section of my Tagbits Guns, I've designed a special mount for this sensor type. I'll be building the gun in the next few days:

AMP-lified

The Milestag CORE and UMT PCBs use 0.1" Vero connectors. These are a pain to use in quantity as every cable has to crimped manually. I've started using AMP 0.1" IDC connectors instead. These are much faster to wire:

A friend of mine uses fine snipe nose pliers to force the wire onto the connectors. I found this unsatisfactory so I made myself an IDC crimp tool from a M8 bolt:

This pushes the cable into the IDC connector nicely:

Battery Cover

Whilst getting ready to try out my single sensor Milestag gun I decided that I needed to re-design the battery cover on the gun body. Previously this had been quite thin and had chamfered, circular tabs that were proving difficult to print as the filament often failed to adhere to the layer below as the radius increased with the chamfer:

I redesigned the cover to have rectangular tabs. These should be easier to print with a chamfer:

I then subtracted this shape from the gun body, and increased all the edges by 0.2mm in size to allow for a good fit.

As the gun body is quite large, it takes a long time to print so I cut out from my model the part I was interested in and printed that:

I then printed the new battery cover:

The new cover slots nicely into the body cut outs and does not need any finishing to make it fit:

Sensor PCBs 2

I've just taken delivery of my Milestag Compatible sensor PCBs:

I'll be making these available ready made and in kit for at Tagbits in the next few days.

TSOP4856

I've just included Vishay TSOP4856 sensors at Tagbits

The Full Monty

Here is a pic of my RepRap complete with heated chamber, acrylic door and filament spool holder. It's printing a grip section from one my Milestag guns.

At the bottom right you can see the hot air gun that I use to maintain the chamber temperature. I keep the machine in my garage and it struggles to get up to temperature with heat from the heated bed alone.