Spider Without a Web

[Logan Novice]

Here's the spider I just finished for my PM1127. It has an extended mounting collar (a hollow "nose" if you will) that fits inside the spindle bore and mounts to the spindle end pulley assembly using two screws in place of the shorter OEM screws. Because I am a novice hobby machinist, this project did not go as smoothly as I had hoped. This is actually my third attempt at getting the mounting screws properly position to mate with the spindle pulley and the spider screws correctly aligned along the circumference. I included those errors in the images (I could have just painted it and concealed that fact) to demonstrate to others that an error does not have to equal failure. We can recover the material to live another day.

 

[brino]

Another project I need to get to.....

Yours looks well done!

Thanks for sharing it.

-brino

 

[Logan Novice]

Another project I need to get to.....

Yours looks well done!

Thanks for sharing it.

-brino

I installed 1/4 - 20 set screws and, at this late moment and with the advice of another hobby machinist, I may have made a mistake there. I now think I'd should have chosen a finer thread. So I will modify this to a slightly larger set screw - at least 5/16-24.

 

[woodchucker]

I installed 1/4 - 20 set screws and, at this late moment and with the advice of another hobby machinist, I may have made a mistake there. I now think I'd should have chosen a finer thread. So I will modify this to a slightly larger set screw - at least 5/16-24.

1/4 20 is fine... that looks like a piece of steel... one honking big piece. I hate to show you what my spider looks like... My spindle is not that big, so a piece of aluminum and nylon 1/4 20 screws. That way it doesn't mar the piece hanging out. works fine.

 

[Weldingrod1]

Probably too late, but 1/4-28 is the NF size...

Sent from my SM-G892A using Tapatalk

 

[Dhal22]

Looks pretty good to me.

 

[mickri]

1/4-20 should be fine. A nice thing about a 1/4-20 thread is one full revolution is .050. You can almost eye ball how much you need to screw in or out when dialing something in. 5/16-24 or 1/4-28 gives you an odd distance and you have to rely on your DI when dialing in. You are not work holding with a spider. The spider is only to keep the work centered in the spindle. So no need to over tighten the screws. Also you need a nut on the set screw to keep it locked in place. Otherwise vibration will cause the set screws to loosen.

 

[Logan Novice]

1/4-20 should be fine. A nice thing about a 1/4-20 thread is one full revolution is .050. You can almost eye ball how much you need to screw in or out when dialing something in. 5/16-24 or 1/4-28 gives you an odd distance and you have to rely on your DI when dialing in. You are not work holding with a spider. The spider is only to keep the work centered in the spindle. So no need to over tighten the screws. Also you need a nut on the set screw to keep it locked in place. Otherwise vibration will cause the set screws to loosen.

Thank you. I am never too old to learn. That's a lot of very helpful data.

 

[Logan Novice]

Update:
I took "mickri's" advice and decided to stay with the 1/4x20 for the advantage he mentioned. Trying to find a screws with brass tips (I know, I could just use solid brass screws - but that's no fun) took me several places and I didn't like the prices. So I decided to make some.
I made a slug through which I could mount the screws in the chuck and locked it all down with two nuts. Mounted it in the lathe and faced the ends then drilled 5/32 to about .100 depth. Turned a pin on a piece of brass rod to fit into the hole and cut off enough of the rod to stand proud of the end of the screw, then sweat soldered the brass to the screw. Turned it all down and presto, brass tipped screws.

 

[epanzella]

I use 1/4-20 or 1/2-20 for all my home made gizmos. 1 revolution = 50 thou. Easy for my old brain to process.