Seeking resistor heater recommendations
Posted by leadinglights
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Seeking resistor heater recommendations May 19, 2015 02:37PM |
Registered: 12 years ago Posts: 1,450 |
On all of the hotends I have made to date I used Welwyn 7W W22 resistors which are 7mm diameter by 22mm long and I have never had a failure but am looking for something physically smaller to try to fit a whole bunch of hotends close together. I see that there are several makes fitting a 5.5mm diameter by 12.7mm long format which would be great - has anybody got types (Manufacture and range/part no) which they can recommend, or which to avoid.
Mike
Mike
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Re: Seeking resistor heater recommendations May 19, 2015 02:48PM |
Registered: 8 years ago Posts: 5,232 |
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Re: Seeking resistor heater recommendations May 19, 2015 02:52PM |
Registered: 10 years ago Posts: 14,672 |
Most people use cartridge heaters these days, not resistors. You will find a wide range of 6mm cartridge heaters on ebay, and smaller one elsewhere e.g. here [reprappro.com].
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Re: Seeking resistor heater recommendations May 19, 2015 03:22PM |
Registered: 12 years ago Posts: 1,450 |
I tried heater cartridges when they first came out but had 4 failures out of 5 - one burned out after ca 20 hours, one case short, one open circuit and one with a resistance of 13 Ohms. I would prefer to stick to resistors until I am convinced that there is a quality product on the market..
By the way, o_lampe, don't try your current controlled PSU idea, the power dissipation depends on the resistance - formula is Power = I squared R.
By the way, o_lampe, don't try your current controlled PSU idea, the power dissipation depends on the resistance - formula is Power = I squared R.
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Re: Seeking resistor heater recommendations May 19, 2015 03:38PM |
Registered: 10 years ago Posts: 869 |
Or perhaps you need to find a better source especially if the 4 of 5 came from the same batch and/or source. I've never had an issue with a cartridge heater failing. The only time that I've ever had to replace them is for design considerations.Quote
leadinglights
I tried heater cartridges when they first came out but had 4 failures out of 5 - one burned out after ca 20 hours, one case short, one open circuit and one with a resistance of 13 Ohms. I would prefer to stick to resistors until I am convinced that there is a quality product on the market..
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Re: Seeking resistor heater recommendations May 19, 2015 04:06PM |
Registered: 12 years ago Posts: 1,450 |
They actually came from two batches, both 24V and 12V - I originally mentioned the problem on this forum about a year ago [forums.reprap.org]
There are also two other factors to consider, I use 24V as far as possible and have not yet seen smaller cartridges in 24V. Also, an axial heater works better in my multi-extruder design.
I will try the heater that dc42 mentioned but I will reserve my options and mainly investigate resistors.
There are also two other factors to consider, I use 24V as far as possible and have not yet seen smaller cartridges in 24V. Also, an axial heater works better in my multi-extruder design.
I will try the heater that dc42 mentioned but I will reserve my options and mainly investigate resistors.
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Re: Seeking resistor heater recommendations May 20, 2015 02:51AM |
Registered: 8 years ago Posts: 5,232 |
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Re: Seeking resistor heater recommendations May 20, 2015 04:55AM |
Registered: 10 years ago Posts: 14,672 |
Quote
leadinglights
I use 24V as far as possible and have not yet seen smaller cartridges in 24V.
RepRapPro does a 19V version, see [reprappro.com]. It should be OK on 24V if you restrict the maximum PWM.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Re: Seeking resistor heater recommendations May 20, 2015 06:49AM |
Registered: 12 years ago Posts: 1,450 |
Thanks dc42, I will send for one from RepRapPro to try. I suspect though that in the end I will in the end keep to resistors - one by Vishay (part number RWM041022ROJR15E1) is categorized all the way up to 450C.
o_lampe, The resistance of an aluminum hot end block made from a 1cm cube would be about 28 microOhms so to get it to dissipate 20 watts would take 2670 Amps - the wires would be too thick for me.
o_lampe, The resistance of an aluminum hot end block made from a 1cm cube would be about 28 microOhms so to get it to dissipate 20 watts would take 2670 Amps - the wires would be too thick for me.
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Re: Seeking resistor heater recommendations May 20, 2015 09:27AM |
Registered: 10 years ago Posts: 14,672 |
Quote
leadinglights
Thanks dc42, I will send for one from RepRapPro to try. I suspect though that in the end I will in the end keep to resistors - one by Vishay (part number RWM041022ROJR15E1) is categorized all the way up to 450C.
450C is a good maximum temperature, and the price is good too (GBP0.43 from Farnell). Getting good thermal contact between the resistor and the heater block won't be easy though, and I don't think the usual thermal transfer pastes are any good at those temperatures.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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Re: Seeking resistor heater recommendations May 20, 2015 09:27AM |
Registered: 8 years ago Posts: 5,232 |
Quote
leadinglights
o_lampe, The resistance of an aluminum hot end block made from a 1cm cube would be about 28 microOhms so to get it to dissipate 20 watts would take 2670 Amps - the wires would be too thick for me.
That´s a lot! But your plans were to build a hole bunch of hotends, so you could design them in a different way to give them much more resistance.
Especially where the heat is needed around the nozzle.
Probably this is one step too far for now...
-Olaf
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Re: Seeking resistor heater recommendations May 21, 2015 04:48AM |
Registered: 12 years ago Posts: 1,450 |
Quote
dc42
Quote
leadinglights
Thanks dc42, I will send for one from RepRapPro to try. I suspect though that in the end I will in the end keep to resistors - one by Vishay (part number RWM041022ROJR15E1) is categorized all the way up to 450C.
450C is a good maximum temperature, and the price is good too (GBP0.43 from Farnell). Getting good thermal contact between the resistor and the heater block won't be easy though, and I don't think the usual thermal transfer pastes are any good at those temperatures.
I do have a tiny amount (0.5ml) of a pyrolytic graphite thermal transfer compound which is astonishingly conductive up to about 700C but probably have not enough for this job. I have been looking at Deepcool Z5 which is supposed to be good to 300 degrees but can't find in the U.K.
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