Damaged 60 1/2 block plane thread - replacement?!

[jsjwilson]

Hi All.

I seem to have some how stripper the thread on my 60 1/2 block plane. Its stripped at the wider diameter bit that advances the blade.

Is it possible to get spare parts for these? Or do I need to get another?

 

[Derek Cohen (Perth Oz)]

Recut the thread if you can get a matching dye.

Regards from Perth

Derek

 

[Phill05]

Not sure but I think I have a spare one I can have a look in the shed in the morning, It's tipping down with rain at the moment.

 

[Phill05]

This is the one I was thinking of but I am now unsure if it will be the right one for your plane, let me know your sizes.

 

[jsjwilson]

This is the one I was thinking of but I am now unsure if it will be the right one for your plane, let me know your sizes.

View attachment 189870

Thanks for trying to help, but this is sadly not the right one.

 

[Fergie 307]

If you know the thread just search for knurled head screw. Easy if it's metric, not so much if imperial. What state is the thread it screws into?
Alternatively get a new bolt or screw with sufficient thread and just cut off the threaded part of the original, drill a suitable sized hole in the knurled top and tap it to suit then screw the new rod in with some loctite permanent.
Or take it to a local machine shop or men's shed and get a new one made.
If the thread it goes into is knackered as well then it gets more problematic. Maybe Helicoil to the nearest available metric size if it's Imperial, then getting a knurled screw to fit would be a doddle.

 

[ChaiLatte]

Please could you post a picture of the other parts with which the screw interfaces as well as a mockup of them assembled.

Your picture above and your written description implies there are threads of two different diameters (and possibly two different pitches on the screw). The damaged portion sure looks bigger and finer than the undamaged lower portion.

Looking around at pictures of 60 1/2 planes, I cannot find any screws that look like the one you show. If we can identify the diameter, pitch and hand of the required threads, making a replacement that screws into the knob, as suggested above, is easy.

 

[Fergie 307]

Please could you post a picture of the other parts with which the screw interfaces as well as a mockup of them assembled.

Your picture above and your written description implies there are threads of two different diameters (and possibly two different pitches on the screw). The damaged portion sure looks bigger and finer than the undamaged lower portion.

Looking around at pictures of 60 1/2 planes, I cannot find any screws that look like the one you show. If we can identify the diameter, pitch and hand of the required threads, making a replacement that screws into the knob, as suggested above, is easy.

Good observation. I hadn't looked closely enough at the picture.
As you say it does look as though the bottom is smaller, and with a coarser pitch than the top. How odd.

 

[jsjwilson]

Please could you post a picture of the other parts with which the screw interfaces as well as a mockup of them assembled.

Your picture above and your written description implies there are threads of two different diameters (and possibly two different pitches on the screw). The damaged portion sure looks bigger and finer than the undamaged lower portion.

Looking around at pictures of 60 1/2 planes, I cannot find any screws that look like the one you show. If we can identify the diameter, pitch and hand of the required threads, making a replacement that screws into the knob, as suggested above, is easy.

There are two different diameters. The smaller, is fine with no issues. The smaller, most distal to the head, attaches to the iron base. The larger diameter fixes to the pictured metal clip. This sits in a groove on the base of the plane and on the other side, two notches slot into the blade and which allows the blade to be advanced. I am not sure why it needs two diameters on the screw. And yes, it is the larger diameter that is gubbed. The thread on the metal clip also looks bad, but looks like it would be retrievable with a tap. I have a metric tap and die and this size looks imperial! I'll take some more pics later to illustrate the above. Thanks for your help.

 

[Limey Lurker]

Please could you post a picture of the other parts with which the screw interfaces as well as a mockup of them assembled.

Your picture above and your written description implies there are threads of two different diameters (and possibly two different pitches on the screw). The damaged portion sure looks bigger and finer than the undamaged lower portion.

Looking around at pictures of 60 1/2 planes, I cannot find any screws that look like the one you show. If we can identify the diameter, pitch and hand of the required threads, making a replacement that screws into the knob, as suggested above, is easy.

Using spring calipers on the screen of my monitor, the threads per unit is the same at both ends of the screw.

 

[Fergie 307]

Using spring calipers on the screen of my monitor, the threads per unit is the same at both ends of the screw.

I was looking at the angle of the threads. Those at the lower end appear to be at a different angle to those at the top, implying a coarser pitch. Doesn't help that it is at an angle. Be interesting to see the full set up. Can't really get my head around how it works.
But with potentially two different sizes I can see it having to be made specially. Easy enough with a screwcutting lathe, or with dies if you can get the shaft accurately machined to start with.

 

[ChaiLatte]

Using spring calipers on the screen of my monitor, the threads per unit is the same at both ends of the screw.

That is good to know.

However, that leaves us with an issue that requires explanation (I am using now using terms aligned with those used by jsjwilson above): if the threads are the same pitch (and same hand), the metal clip will not advance relative to the iron base when the knob is turned.

You can prove this to yourself if skeptical: put two nuts onto a bolt. hold the nuts steady and turn the bolt. The bolt moves relative to the nuts, but the distance between the two nuts stays constant. Hence, you might need to propose a way that the blade is advanced with this setup.

Those at the lower end appear to be at a different angle to those at the top, implying a coarser pitch.

Making judgements based on the helix angle could be misleading because it is a function of diameter. If you put a 1mm pitch thread on a 6mm dia. rod, it will look steeper than a 1mm pitch thread on a 10mm dia. rod.

If we see the thing assembled, we can work backwards from the fact that the arrangement must allow adustment of the blade. That will circumscribe possiblities for the threads.

 

[rob1693]

The stripping occurs when you don't release the frog cam when advancing or retracting the iron, gave my dad one and he's knackered his

 

[Fergie 307]

I think your best bet is going to be to find someone with a suitable lathe to make a new one. Maybe a post in general metal working? If there is someone near to you it would be easy to make a new one, anyone having the machine will also probably have the means to identify the thread.
Or a local engineering firm, only issue you might have there is with it potentially being imperial.

 

[deema]

That took some doing, you must have had 3 weetabix that day…..

 

[Fergie 307]

That is good to know.

However, that leaves us with an issue that requires explanation (I am using now using terms aligned with those used by jsjwilson above): if the threads are the same pitch (and same hand), the metal clip will not advance relative to the iron base when the knob is turned.

You can prove this to yourself if skeptical: put two nuts onto a bolt. hold the nuts steady and turn the bolt. The bolt moves relative to the nuts, but the distance between the two nuts stays constant. Hence, you might need to propose a way that the blade is advanced with this setup.



Making judgements based on the helix angle could be misleading because it is a function of diameter. If you put a 1mm pitch thread on a 6mm dia. rod, it will look steeper than a 1mm pitch thread on a 10mm dia. rod.

If we see the thing assembled, we can work backwards from the fact that the arrangement must allow adustment of the blade. That will circumscribe possiblities for the threads.

Fair point re the helix. But I am with you on the function, seems a strange idea that to move the blade you would be undoing the rod from it's fixing in the base. And as you say the two parts won't move relative to one another. No doubt it will make sense if we can see it in situ.

 

[Fergie 307]

If you really get stuck then pm me. I will happily make one for you. I would need the other part as well.
Looking at the state of the thread on the rod, not sure I share your optimism that it will clean up ok. I suspect that would probably need doing as well

 

[MorrisWoodman12]

I have a feeling based upon owning one many years ago coupled with a dodgy memory that one thread is right handed while the other is left handed. Looking at the photo sort of confirms this hence the two different diameters.

 

[Amplidyne]

I'm not sure about this, but those threads look like a different size to me as already said. They also look the same pitch, but the steeper helix angle implies a double start thread. It does actually look like that, but can only really be ascertained by examination. It makes sense in the the parts would move apart when the thread was turned. It also complicates things for anyone making one. Certainly not insurmountable, but just more complicated. Any maker would need to examine the whole plane preferably to take sizes and threads off it.

 

[Amplidyne]

I have a feeling based upon owning one many years ago coupled with a dodgy memory that one thread is right handed while the other is left handed. Looking at the photo sort of confirms this hence the two different diameters.

They both look like a RH thread to me, I thought one might be LH as well but in this case I don't think so. See my other post.
I hope I'm wrong actually!