Sunday, December 2, 2012
J-Head Mk V-BV hot-ends shipping Monday!
On Monday, December 3rd, the first J-Head Mk V-BV hot-ends start shipping. Above, on the left, is the J-Head Mk V-BV and, on the right, is the J-Head Mk V-B. The only differences are all thermistor-related and they are as follows: The thermistor itself, the mounting location, and the size of the thermistor hole. Otherwise, both hot-ends are identical.
I decided to add the trailing "V" to the J-Head model number solely in an attempt to avoid confusion and bring attention to the fact that the thermistor changed. Historically, the J-Head hot-end has always used the type 1 (EPCOS) thermistor and this is the first time the thermistor has had to change. The "V" has been added to denote that thermistor 5 will have to be selected in most firmware configurations.
In addition, the thermistors are shown separately, above, in the center. The new thermistor is on the left and the original thermistor is on the right.
The J-Head Mk V-BV was created due to the fact that EPCOS is no longer manufacturing the original type 1 thermistor. While a substitute appears to be available, the lead time is excessive and I have noticed that it is only available in large quantity orders. After some testing, I selected the type 5 thermistor as it is already used in other hot-ends and has been proven to be able to perform the job at hand.
The information, on the new thermistor, is as follows:
Part Number: 104GT-2
Description: NTC 100k ohm 3%
Data Sheet: High Heat-Resistance and High Sensitive Thermistor
Diameter of Glass Bead: 1.35mm +-0.15mm
Length of Glass Bead: 3mm +-1mm
Lead Length: 45mm +-1mm
Lead Diameter: 0.15mm to 0.18mm
If using Sprinter firmware, select temperature table #5.
Please note that I do have a limited supply of brass nozzles that are already drilled out for the original thermistor. During the transition, to the new thermistor, these nozzles may have the new thermistor hole added and, as a result, will be able to handle either thermistor. If the thermistor fits the small hole, it will be the new thermistor.