Tight-Fitting Bock Housing Threads

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hokie

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May 29, 2017
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For the life of me, I cannot cleanly thread a #6 bock housing into the M7.9-0.6 threads I tap into a section. Like, I can't even get them started most of the time, I end up beginning to cross-thread or chew up the threads on the housing. I've only been somewhat successful after lots of sanding and cramming the threads together over and over again, but the housing ends up looking like a mess. I know I'm not the only person that has had to deal with this because I've seen a discussion or two about it, but I'm not sure if I've seen specific solutions. Does anyone have any suggestions as to how to deal with such a headache?

I thought I remember seeing mentions (on a forum or a product listing) of the bock housing being more oval than round due to poor tolerances at the factory and suggestions for a different size tap to build in allowances for that variance, but I can't find it anymore. Not sure if that would be super helpful unless it's available to purchase anywhere. With all of the people buying bock nibs and the associated taps for sale all over the place, I would have assumed there would be more discussion around it. Is it a personal problem?

Thanks in advance!
 
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hokie

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I used a letter "L" bit which is 7.3660 and pretty darn close to 7.4, but I can try to bump it up to letter "M". Would be curious what others use.
 

FGarbrecht

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Similar problem with Bock #5 housing. I ended up using the housing tap to create a homemade die to use as a thread chaser on the housing. Re-cutting the pre-formed housing threads with the chaser takes a tiny tiny amount of material off the housing threads and makes the fit much better.

Here's what I did. Cut a thin disk of aluminum, 0.5" thick is fine. Center drill with the bit you use with your Bock tap, then use the tap to cut threads in the die. I then cut a few grooves into the die threads to allow chip clearance (I don't remember what I used for this but probably was a little jigsaw blade that I stuck through the hole and sawed by hand). The grooves don't need to be deep as the chips are extremely tiny. The other thing I do is to use the tap to cut the internal section threads from BOTH ends of the section to make sure the threads are really well formed and completely cut. This usually does the trick although I sometimes still have a bit of difficulty and the nib/feed assembly can pull loose from the housing when installing or taking out the housing from the section.
 

hokie

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Similar problem with Bock #5 housing. I ended up using the housing tap to create a homemade die to use as a thread chaser on the housing. Re-cutting the pre-formed housing threads with the chaser takes a tiny tiny amount of material off the housing threads and makes the fit much better.
Thanks for the details! It's a shame we have to resort to that kind of process for what should be a simple thing.
 

Jontello

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I was having a similar problem with some taps I bought in a group buy. I knew I was doing everything right. So I contacted Phil from Beaufort ink who also carries these taps for bock 5 and 6 nibs. He said that when he gets his taps made he actually sends them the bock housing to test and make sure the fit is right. I don’t think that is the case when group buys happen. So what I did is ordered one of his taps and it worked. No more struggling to make things work and struggling. My suggestion would be to buy a tap from Phil instead of struggling like you are. Just my opinion.
 

FGarbrecht

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I was having a similar problem with some taps I bought in a group buy. I knew I was doing everything right. So I contacted Phil from Beaufort ink who also carries these taps for bock 5 and 6 nibs. He said that when he gets his taps made he actually sends them the bock housing to test and make sure the fit is right. I don’t think that is the case when group buys happen. So what I did is ordered one of his taps and it worked. No more struggling to make things work and struggling. My suggestion would be to buy a tap from Phil instead of struggling like you are. Just my opinion.
This is probably a good idea. I don't think these are all that expensive (at least compared to the custom triple start taps and dies!)
 

hokie

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I was having a similar problem with some taps I bought in a group buy. I knew I was doing everything right. So I contacted Phil from Beaufort ink who also carries these taps for bock 5 and 6 nibs. He said that when he gets his taps made he actually sends them the bock housing to test and make sure the fit is right. I don’t think that is the case when group buys happen. So what I did is ordered one of his taps and it worked. No more struggling to make things work and struggling. My suggestion would be to buy a tap from Phil instead of struggling like you are. Just my opinion.
I bought my tap in the most recent group buy, so you may be on to something (though they are TapCo like Phil's!). I think I'm going to go ahead and buy from Beaufort Ink anyway when they are back in stock. I really want to avoid having to potentially damage the housings and adding more steps to an already laborious process. Having a little QA in the process adds to the peace of mind. Thank you!
 

RangeRat

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Interesting.....I also purchased a Bock #5 nib tap in the last group buy and have had a heck of a time getting the nib housing to thread in. I’ve only made one section from scratch so far and while I did finally get the housing threaded and seated, it is seized in there forever. Even if I could remove it, I imagine the housing threads are buggered up. Makes me curious if maybe there is a discrepancy with all the nib taps from that buy?
 

Carl Fisher

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I assume you guys are waiting for the material to completely cool before threading? If you thread while hot you're introducing all sorts of issues with pieces expanding/contracting with the heat introduced from drilling.
 

hokie

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Interesting.....I also purchased a Bock #5 nib tap in the last group buy and have had a heck of a time getting the nib housing to thread in. I’ve only made one section from scratch so far and while I did finally get the housing threaded and seated, it is seized in there forever. Even if I could remove it, I imagine the housing threads are buggered up. Makes me curious if maybe there is a discrepancy with all the nib taps from that buy?
I would love to hear from others who have purchased in the group buy too. My Jowo taps seem fine. It's just the Bock for me. I wonder if people are suffering in silence!
 

hokie

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I assume you guys are waiting for the material to completely cool before threading? If you thread while hot you're introducing all sorts of issues with pieces expanding/contracting with the heat introduced from drilling.
I do indeed wait for the material to cool... or at least I have most certainly re-tapped the threads in frustration with no apparent impact on the "threadability". The fit is so bad, I can't even get the housing to partially engage. If I try to use some pressure, I get what feels like cross threading happening and a bit of a mangled housing. Interestingly, when I thread Delrin, just as a test, I get a *very* tight fit, but better engagement. Maybe the Delrin stretches ever so slightly?
I feel as if either there is a Bock manufacturing issue, the housing threads weren't measured right in the first place, or something has changed since hobbyists started using Bock nibs. Frustrating for me because I bought a whole bunch of Bock nibs and would hate to not be able to use them.
 
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