Shopsmith Lathe face shield

[wa2crk]

Hi Gang
I bought the face shield on sale and went to install it today. I used the provided self tapping screws ( I hate those things) and installed the bracket. I mounted the shield and when I tried to move the shield the bracket immediately popped off the carriage. It seems that the carriage casting is too thin to hold with only one or two threads holding the bracket to the very thin casting. I mounted the shield to my Delta midi lathe by drilling and tapping the 10-32 screw holes into the cast iron bed and it it is much stronger. I also re-tapped the two holes in the carriage on the SS and used standard 10-32 screws but I have not tried to mount the shield again as yet. I may have to a put a nut on the inside of the carriage but there is precious little room.
Overall I am happy with the shield and the quality.
I don't want to drill any more holes in the carriage because I think that would weaken that area too much
Anyone else who bought the shield please let me know how you make out.
Bill V

[benush26]

This is not specific to the shield, but mounting to thin sheet metal or inaccessible from behind.
When I don’t need the mounting plate flush to the backing metal, I use a rivnut. I’ve used a cheap method to install them (had to go to YouTube to find the video similar to what I do)
https://youtu.be/yodgSo2k1GA
I like them in cast iron when I don’t want to tap the hole,
Hope this helps or at least gives you an idea.

Be well,
Ben

[wa2crk]

Ben
Almost forgot about those things. Used them years ago installing two way radio systems in fire trucks, police cars etc.
The tool resembled a pop rivet tool and was manually activated. I think that I may have seen a similar system at Harbor Freight. Thanks for the reminder.
Bill V

[jsburger]

Ben
Almost forgot about those things. Used them years ago installing two way radio systems in fire trucks, police cars etc.
The tool resembled a pop rivet tool and was manually activated. I think that I may have seen a similar system at Harbor Freight. Thanks for the reminder.
Bill V

I have a question. I have 3 SS lights that I think have the same bracket as the lathe shield. They came with a drill bit and the self tapping screws. Two are installed on two of my head stocks and the third is installed on my stand mounted band saw. They have the same goose neck as the shield I would think. They have been there for years with no problem.

If any of the castings are thinner than the table carriage I would think it would be the band saw. Again, no problems with that one after years of use. Did you get a drill bit from SS with the kit?

I agree with you. I don't like self tapping screws either. I think the problem is improper installation. You must have the proper sized drill bit. Then you must use extreme pressure to start the screw so it starts to cut the threads properly. Also make sure it is started straight. No drill driver, a hand screw driver is the only way. Then don't over tighten the screw.

[BuckeyeDennis]

As far as I’m concerned, self-tapping metal screws are for folks who don’t have a proper tap set. If I’m in a hurry, I’ll chuck the tap up in a reversible drill, and tap in on low speed. I first saw this technique used by a machine-tool rebuilder, tapping good-sized bolt holes in a cast-iron machine base. These days, I only hand tap if the workpiece is so fragile that I might strip it by not getting the feed pressure just right.

That said, thread-forming plastic screws are a different animal. They force the plastic to flow, and form nice strong threads.

For what it’s worth, the strongest threads in metal are also produced by forming, aka “rolling”. Instead of cutting through the grain of the metal matrix, it deforms the matrix, changing the shape without sacrificing strength, and even enhancing it due to work hardening. Production thread-rolling dies are expensive (roughly $5K each, IIRC) but the operation is so fast that in quantity, it costs less than cutting the threads.

[jsburger]

As far as I’m concerned, self-tapping metal screws are for folks who don’t have a proper tap set. If I’m in a hurry, I’ll chuck the tap up in a reversible drill, and tap in on low speed. I first saw this technique used by a machine-tool rebuilder, tapping good-sized bolt holes in a cast-iron machine base. These days, I only hand tap if the workpiece is so fragile that I might strip it by not getting the feed pressure just right.

That said, thread-forming plastic screws are a different animal. They force the plastic to flow, and form nice strong threads.

For what it’s worth, the strongest threads in metal are also produced by forming, aka “rolling”. Instead of cutting through the grain of the metal matrix, it deforms the matrix, changing the shape without sacrificing strength, and even enhancing it due to work hardening. Production thread-rolling dies are expensive (roughly $5K each, IIRC) but the operation is so fast that in quantity, it costs less than cutting the threads.

I absolutely agree with you. However, how do you expect SS to sell these brackets to the masses? Many woodworkers don't even know what a tap is let alone the proper drill size for the tap. They do supply the proper drill bit for the screws so that the average person can be successful.

We are talking about an add on here that needs to be attached. Not a manufacturing process from the OEM.

[wa2crk]

Hi Gang
Thanks for all the input. John B, I don't know how robust the light bracket is but The goose neck for the shield is about 5/8 inch in diameter and takes a good amount of force to move it. Which is what probably made the bracket pull out. I re-drilled the holes using the proper sized drill according to my machinist's guide and re-tapped with a proper tap. I will see if this proves adequate. I also replaced the self tapping screws with standard machine screws which seem at this time to give a better hold.
Bill V

[JPG]

I am gonna guess that those 'self tapping' screws are actually 'self threading' screws with a course thread similar to sheet metal screw pitch.

I like self tapping screws that produce standard sae nc pitch threads.

[wa2crk]

JPG
The screws provided were 10-32 and I can not discern any difference between the threads on them and the standard screws that I used. However the standard screws seemed to have a better hold than the original.
Bill V

[JPG]

Yep they are self threading. I assume they were very short, so the tapered tapping end may have been not clear of the inner surface.