Author Topic: kWeld - "Next level" DIY battery spot welder  (Read 98657 times)

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Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #400 on: October 02, 2017, 12:42:02 am »
Cool sounds good enough.


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Offline joddi

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #401 on: October 04, 2017, 11:12:46 am »
I want the system to allow welding at 50J with one second repetition rate. This means that the PSU needs to supply 50J / 0.1 * 1sec = 500W on average. (The 0.1 is the system efficiency)

Nice target, but it also means your whole system has to be capable to disipate continuously 500W of heat somewhere...

I'm waiting for next batch of your electronics to order one. I need to weld copper braid to brass sheet with oposite electrodes, so probably more pulse energy will be necessary, but I don't care much about repetition rate (30s would be ok). I'm thinking of 500J pulses or maybe more and I'm prepared to double power MOSFET switch if necessary.
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #402 on: October 04, 2017, 07:42:02 pm »
your whole system has to be capable to disipate continuously 500W of heat somewhere...
Most of the heat is dissipated in the super capacitors, which is why they will receive a decent fan. And this 50J/1sec target is not a continuous one, because the electrodes also receive substantial heat from the weld spot itself. A fixed electrode system could handle this, but the handheld system needs regular cooling breaks. I have set the 1sec goal because I do not want to limit the usability because one constantly had to wait for the capacitors to recharge.

I'm waiting for next batch of your electronics to order one. I need to weld copper braid to brass sheet with oposite electrodes, so probably more pulse energy will be necessary, but I don't care much about repetition rate (30s would be ok). I'm thinking of 500J pulses or maybe more and I'm prepared to double power MOSFET switch if necessary.
I don't think that kWeld is up to this task. I tried to weld two 0.1mm copper sheets together without success. Copper requires a significantly higher output power, and 1500A is not enough.
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Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #403 on: October 04, 2017, 08:19:39 pm »
Kweld is intended for battery tab spot welding. Maybe you could do a diy spot welder with a MOT.


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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #404 on: October 07, 2017, 04:08:53 am »
The capacitor charger test load has arrived, and I couldn't resist to make a first test with a higher load. Results: 35A at 8.5V -> 297W. Hottest spot of the charger are the large heat sink and the inductors: 50°C. It amazes me how small power circuits can be with modern components  8)

Sadly, I had to stop here because the server PSU seems to have problems, it reaches 105°C at one spot of its PCB. I'll have to solve that before continuing. I have another ten bulbs waiting (these are 50W).
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Offline anishkgt

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #405 on: October 07, 2017, 04:59:10 am »
That's a lot of work your going through frank but I guess it's part of the fun and it pays off at the end


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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #406 on: October 07, 2017, 07:30:14 am »
it's part of the fun and it pays off at the end
Definitely the fun, but I am also learning a lot. This is my first four phase buck converter, and the amperage is also an order of magnitude more than what I did before. I am also using Infineon's OptiMOS5 MOSFETS for the first time. They are extremely fast, have integrated snubbers, and their diode reverse recovery charge (that quickly causes ringing/EMI problems) is lower than everything else that I know. I have attached pictures from one of the switch nodes at 35A load current, clean as a whistle.

And I hope that it will also pay off, not necessarily only as an accessory for the welder, but also as a high power laboratory supply. A regular 0-12V 0-80A lab supply can easily hit 1000€ or more, this one an order of magnitude cheaper.

And last but not least, I am developing an own business as an engineering service provider, and am collecting references.
« Last Edit: October 07, 2017, 09:24:18 pm by tatus1969 »
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Offline anishkgt

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kWeld - "Next level" DIY battery spot welder
« Reply #407 on: October 07, 2017, 07:36:09 am »
Well that's good to know. To be honest, the first paragraph was like French to me but I did understand your point.

The second is quite interesting and if it can be developed into bench power supply then I would be interested to buy one from you if your selling it latter as bench PSU itself with mV resolution. That is of course once your done with the kWeld project.


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Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #408 on: October 23, 2017, 01:03:27 am »
I very recently took delivery of a Tiertime UP! BOX 3D printer (from fellow forum member Toploser).

As part of my 'getting to know the printer' process I have printed various small parts that I needed. I decided to also print the kWeld case as a test of the warping on large area prints. I always print in ABS so warping is a fact of life and needs careful consideration with regard to bed temperature and object placement on the bed.

I told Frank about my intention to produce a test print of his case ad he asked that I share the results with you here.

The result is far from perfect but then I had expected that as I used all default settings without any additional precautions against warping. The print is not a basket case but it did suffer warping at two corners of the raft and this distorted the corners of the case slightly. I will list the issues I discovered with the print below. Some are due to the default print settings, my failure to adequately preheat the build plate, whilst others are likely minor issues with the case design.

1. Case top is printed inverted to avoid masses of support material. This means the top surface will not be as fine a finish as if the case were printed the other way up.

2. When printing objects with a large base area in ABS, there is always the risk of the ABS lifting at the extremities of the print. This is usually countered by pre-heating the bed for at least 15 minutes and printing in a heated chamber. I failed to adequately pre-heat the build plate and chamber ..... oooops  ;D The result was some warping at two corners of the print.

3. The raft in the UP! series printers is usually pretty good when it comes to ease of removal from the object sat on it. The finish on the objects bottom surface is also pretty good. For some reason the raft did not come away easily from some areas of the case top and I was less impressed with the surface of the stepped down area for the LCD and knob. The 'KWeld' logo on the top of the case also presented some issues as it was not easy to remove the support material without leaving obvious tool marks on the plastic below.

4. The Case top design includes a pair of pillars. I tested their strength when formed in ABS. My conclusion is that they are too fragile and easily break away from case top. I believe these pillars would benefit from a thicker wall or a connical shape with a wider base to carry any lateral load.

I attach pictures of the printer and the parts it produced.

Fraser
« Last Edit: October 23, 2017, 02:24:12 am by Fraser »
 
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Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #409 on: October 23, 2017, 01:05:14 am »
Pictures continued.....

(Including broken pillar detail)
 
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Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #410 on: October 23, 2017, 01:15:02 am »
A picture of the excellent UP! BOX unit and some pictures of another part I just printed.

Of significance about this part is that it was printed in the vertical plane rather than horizontal where ABS warping can be an issue.
I am going to try printing the kWeld case in the vertical plane next to see how it comes out. The raft will attach at the rear so any surface blemishes are out of sight. The print will take 5 hours so may not get done until a bit later, or tomorrow.

I should state that one of the advantages of printing in ABS is that it can be sanded, filled and painted with modelling products, just like an Airfix model kit  :)  I may sand and paint my kWeld case when I have a good print of it. The Kermet Green is just some UP! Fila that I found at half price ! Not everyones choice of colour me thinks  ;D

Fraser
« Last Edit: October 23, 2017, 02:26:43 am by Fraser »
 

Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #411 on: October 24, 2017, 12:49:11 am »
Well the vertical print of the case is under way. Should be finished around 6pm.

It uses a lot of support structure for obvious reasons. The total amount of ABS used is 62g. The conventional inverted flat print uses just over 50g so the additional support material is around 12g. Worth it if the finished product is of good quality though. The ABS filament I am using is genuine higher temperature Tiertime UP! FILA that cost me £10 per 500g reel.

For info, on this print I carried out the correct pre-heat procedure and rotated the object so that the most dense area is facing away from the printers air circulation filter fan. I am wondering if the air flow towards the filter intake on the left hand side encourages faster cooling and shrinkage of the ABS on that side. It is all a learning curve on this new printer. If the print fails, no matter, I will have tried a different approach and discovered its limitations.

Fraser
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #412 on: October 24, 2017, 01:09:00 am »
4. The Case top design includes a pair of pillars. I tested their strength when formed in ABS. My conclusion is that they are too fragile and easily break away from case top. I believe these pillars would benefit from a thicker wall or a connical shape with a wider base to carry any lateral load.
I'll add that to the improvement list, thanks!
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Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #413 on: October 24, 2017, 02:02:55 am »
Frank,

So far that is the only design issue I have found with the case. It is looking good in the printer at the moment. It is like waiting for a baby to be born :)

Fraser
 

Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #414 on: October 24, 2017, 02:10:27 am »
Frank,

I forgot to ask, what design software did you use to create your case please ?

Best Wishes

Fraser
 

Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #415 on: October 24, 2017, 03:27:04 am »
The print is almost done....... it looks OK with just a little warping in the front right corner. I have made a major error though. It made me laugh when I noticed. See if you can spot the error :). 5 hours print time wasted  ;D  It is all good experience  :-+

Fraser

« Last Edit: October 24, 2017, 04:17:09 am by Fraser »
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #416 on: October 24, 2017, 04:49:18 am »
what design software did you use to create your case please ?
Done with Sketchup :-)
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Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #417 on: October 24, 2017, 04:57:03 am »
The print is almost done....... it looks OK with just a little warping in the front right corner. I have made a major error though. It made me laugh when I noticed. See if you can spot the error :). 5 hours print time wasted  ;D  It is all good experience  :-+
Took me some time... Mirrored :palm:  :o
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Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #418 on: October 24, 2017, 05:00:18 am »
Frank,

Yes a real  :palm: moment .... no, make that a  :palm: :palm:  ;D

I stupidly mirrored instead of rotated 180 Degrees !

Lesson learnt  ;D

Fraser
« Last Edit: October 24, 2017, 05:04:57 am by Fraser »
 

Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #419 on: October 24, 2017, 05:15:20 am »
The case print has completed  :)

We already know it is scrap but I can learn from it and see how well the idea of vertical printing worked.

I am actually pretty pleased with the quality of print produced. The finish is very nice with only the rear panel showing the usual evidence of its attachment to the raft. Such may easily be tidied up and polished if it is an issue.

Sadly there is still an unacceptable amount of warping along the length of the rear panel where it was mounted on the raft. Such is a common issue with printing in ABS. The print bed is currently operating at 90C. Some experienced 3D ABS printers suggest 110C and I will experiment at that temperature.

Pictures of the print followed. There was a lot of support material but it came away very easily and I have no issues with that part of the print process. It worked very well indeed.

I placed the first print attempt next to the latest and I note that the latest print looks darker in colour even though it is the same ABS filament. I prefer that colour and the finish on the surface. No problems with the KWeld Logo this time.

Fraser
 

Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #420 on: October 24, 2017, 05:17:26 am »
Pictures continued.....
 

Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #421 on: October 24, 2017, 05:19:23 am »
Pictures continued.....
 

Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #422 on: October 24, 2017, 05:20:51 am »
Pictures continued....
 

Offline tatus1969

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #423 on: October 26, 2017, 10:40:52 pm »
and does it fit? I'm curious.
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Offline Fraser

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Re: kWeld - "Next level" DIY battery spot welder
« Reply #424 on: October 26, 2017, 11:30:42 pm »
I will check.

I can confirm that my UP! BOX printer manages to produce very accurate prints. I needed a plastic sleeve to fit snuggly around a bolt and to have a sliding fit into a tube. I used the dimensions taken from my digital caliper and the resulting 50mm long sleeve was a perfect fit, both on the 6mm bolt and inside the 10.5mm diameter tube. The UP! Software automatically compensates for ABS shrinkage after cooling :)

Fraser
« Last Edit: October 26, 2017, 11:42:53 pm by Fraser »
 


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