3D Printer Enclosure

[OnOff]

My money's on that bfo trannie in the middle, looks a bit crispy.

 

[Sharpend]

My money's on that bfo trannie in the middle, looks a bit crispy.

having looked at it there does appear to be a crispy coating more so at one end than the other. 
goosed or worth repairing? Can you even get that transformer? 

 

[OnOff]

having looked at it there does appear to be a crispy coating more so at one end than the other. 
goosed or worth repairing? Can you even get that transformer? 

Look for numbers on the side and whack em in Google with "transformer" afterwards.  Chances are it'll be something obscure only relative to Makita but you might be lucky. 

Or just meet up some time and you can have one of my old chargers! It'll only cost you a Pret latte!

 

[Sharpend]

Well that may be the better option, I’m down Mitcham way a week Monday! Might have to pop across if time permits.

 

[Geoff1946]

Can you even get that transformer? 

You have more chance of a lottery win in my opinion. 

Good old fashioned mains transformers you can usually find a substitute, but inverter psu types I think are individual design. If anyone knows otherwise, please tell.

 

[Phoenix]

@Onoff

Right, had a look at this a bit more, the third connection on the battery seems to retain its voltage even when the battery is too flat for a makita tool to run, even though some people report it disappearing after running a tool till the battery is flat, so perhaps it is only a +ve temperature output. With that in mind we really should at least try and protect the batteries from being discharged too much, as this is bad for Li-ion batteries.

Came up with the following, which through a quick trial appears to have a reasonable approximation, connected it up, ran the heat gun untill it went off, now it does allow you to release the trigger and start it again, but it wont go for more than a few seconds before turning off again. Took the battery in this state and put it in the makita impact driver and after winding a scew in and out on my bench a few times, I picked up a 4" bit of scrap and a long screw and it impacted it in about 2" before it stopped, so it seems to cut off a tiny bit in advance of what a makita tool would which is about what we want.

It is very simplistic and based a bit on trial and error, and I wouldn't say its perfect. but hopefully it should help stop batteries being accidentally over discharged

R1 and R2 form a voltage divider and the volt drop across both is equal to the battery voltage, the volt drop across R2 is 1/23rd of the total (the remainder being across R1). That means that if the battery is at 18v, the voltage at the mid point is 18/23=0.78v above negative which allows the transistor to turn on, when the voltage is less than 0.6v it will turn off, that equates to a battery voltage of 0.6*23=13.8v. The battery voltage does sag under loead due to its internal resistance, so the sensed voltage does drop below the 0.6v mark, meaning the tool turns off, the voltage then goes back up to above it, meaning it will turn on briefly again if trigger is released and re-pressed and will run for a few seconds before doing the same again

 

[OnOff]

@Onoff

Right, had a look at this a bit more, the third connection on the battery seems to retain its voltage even when the battery is too flat for a makita tool to run, even though some people report it disappearing after running a tool till the battery is flat, so perhaps it is only a +ve temperature output. With that in mind we really should at least try and protect the batteries from being discharged too much, as this is bad for Li-ion batteries.

Came up with the following, which through a quick trial appears to have a reasonable approximation, connected it up, ran the heat gun untill it went off, now it does allow you to release the trigger and start it again, but it wont go for more than a few seconds before turning off again. Took the battery in this state and put it in the makita impact driver and after winding a scew in and out on my bench a few times, I picked up a 4" bit of scrap and a long screw and it impacted it in about 2" before it stopped, so it seems to cut off a tiny bit in advance of what a makita tool would which is about what we want.

It is very simplistic and based a bit on trial and error, and I wouldn't say its perfect. but hopefully it should help stop batteries being accidentally over discharged

R1 and R2 form a voltage divider and the volt drop across both is equal to the battery voltage, the volt drop across R2 is 1/23rd of the total (the remainder being across R1). That means that if the battery is at 18v, the voltage at the mid point is 18/23=0.78v above negative which allows the transistor to turn on, when the voltage is less than 0.6v it will turn off, that equates to a battery voltage of 0.6*23=13.8v. The battery voltage does sag under loead due to its internal resistance, so the sensed voltage does drop below the 0.6v mark, meaning the tool turns off, the voltage then goes back up to above it, meaning it will turn on briefly again if trigger is released and re-pressed and will run for a few seconds before doing the same again

View attachment 11377

I've got those resistors and that transistor. So this needs to be built into the adaptor?

 

[Phoenix]

Yes, two options, either solder the components directly together and heatshrink where required and it'll end up pretty small and secure into a cavity on the adapter with hot melt glue or whatever. Or I could look at getting some small PCBs due by JLCPCB with mointing holes etc, that the adapater would be made to secure it in place with.

The transistor isn't specific btw, just a generic NPN one, its just one of the ones I have to hand

 

[OnOff]

@Phoenix, I'll get back on this maybe this evening for a bit. Nearly ready to print a test section to fit into the Parkside hot air gun. It's a little more complicated where you fit to the tool as you need "female" connectors to go onto the tools "blades".

This was successful, Makita battery to Einhell tool. So the side that connects too the battery is fairly easy. Just blades, in this case 1mm copper, that slot into the battery.



The other side is where it gets fun. In this case cranked copper strip that holds tight to the tool blade:



Not my design this one but I did tweak it. The plastic printed "spring" that holds it into the Einhell tool is quite fragile. I broke it on both adaptors and ended up siliconing the clips on. I use to power my 36V Einhell chainsaw. The adaptors remain removable.

Of course there is no provision for a 3rd pin contact. The cranked copper design makes space tricky to get a 3rd one in. Not impossible mind.

I do have the contacts from a dead Makita battery here I will play with but need more really.

Does your circuit need to go in all adapters, say DeWalt battery to Parkside tool?

 

[Phoenix]

@Phoenix,

Does your circuit need to go in all adapters, say DeWalt battery to Parkside tool?

You'll probably need something, but theres no guarentee it'll be exactly the same. We know that the parkside stuff needs something to turn it on, a 10K resister from negative does this, what is needed might vary, you might find some the same as parkside, and some what something different. Obviously what the battery provides varies between makes as well.

You could just do what every is required to make the tool turn on, but over discharging is bad for Li-ion batteries, so you really ought to have something built in, now some tools might monitor battery voltage themselves, but some might not.

So in summary, yes, but because tools vary and batteries vary, there would have to be differnt permentations for each combination

 

[OnOff]

Too knackered to play with CAD tonight plus can't find my digital Vernier!

Printing this little piece of the adapter I've drawn so far, now, to see how it fits in the hot air gun...it might not!



What I could do with finding is a source of similar female connectors like on this old Makita battery pcb. It'd be a doddle to incorporate in the model:

 

[OnOff]

Close but no banana!



Slides in so far then goes tight, real tight just as it comes up to the blades. Might be the slots for the blade centres are slightly out.



Another go tomorrow!

 

[OnOff]

Just a little sliver to proof the edge detail fits:



That's good. 



Just widened the blade slots in the model and printing a test bit for that. 

 

[OnOff]

Fits OK. A little tweak to make on two slots.



Just need to find a source for these contacts. I searched for: female, double leaf, spring, breadboard, receptacle, contacts etc and all combinations. No luck.

 

[Sidewinder]

Just need to find a source for these contacts. I searched for: female, double leaf, spring, breadboard, receptacle, contacts etc and all combinations. No luck.

Di you mean the yellow one or the bent plated ones?

 

[Sharpend]

I think he is referring to bent plated ones? 

next time I get a duff battery I’ll salvage the contacts before chucking it out. 

 

[Sharpend]

just a thought Onoff, could you make an adapter for Makita to Milwaukee battery? I could then use it in my radio? I don’t mind chucking you some dollar. 

 

[OnOff]

Di you mean the yellow one or the bent plated ones?

The bent plated ones.

 

[OnOff]

just a thought Onoff, could you make an adapter for Makita to Milwaukee battery? I could then use it in my radio? I don’t mind chucking you some dollar. 

M12, M18?

Something like this to attach to the Milwaukee tool:

https://www.thingiverse.com/thing:655904

Then a bit to go onto the Makita battery.

I often plagiarise designs, taking the top of one and the bottom of another then grafting them together. As often as not I'll take an idea on board but do my design from scratch with a Vernier. I a selection of duff tools and batteries from other makes I collect that makes it easier. My trouble is I'm easily bored. Got half a dozen converters on the go on CAD at the mo. I just do it for fun. The material and printing cost is peanuts, time taken to do it and a few test prints runs into several, maybe tens of hours.

You could buy one:

https://www.ebay.co.uk/itm/Milwaukee-M18-18V-Li-ion-Battery-Makita-18V-Li-ion-Battery-Tools-Adapter-/124608102750?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338268676&toolid=10044&customid=EAIaIQobChMIpv7XpYyj8AIVkflRCh0DLAoKEAQYAyABEgJmpPD_BwE

 

[Sharpend]

The first link: is that a replacement fitting to swap on the radio? So that the adaptor replaces the Makita plate that is the radio already? That would be exceptionally useful. 
 

The second link: I don’t have a problem buying one, although never really gave it a thought that they’d be readily available! Only question on the bought option is it looks a little large and don’t know if adding that in would allow the back of radio to shut? 
 

your ones always look neat and compact.