Will a 1/4" rod fit a 7mm tube?

[ramaroodle]

I'm making a jig for use with my laser engraver. The jig calls for a 7mm mandrel rod. Rather than drive 25 miles to Woodcraft to spend $5 for a replacement mandrel rod I'd rather just drive 1 mile to Lowes and get a 1/4" rod. The mandrels are .247 dia. vs .250 for a 1/4" rod. Will that fit into a 7mm tube? They are called "7mm mandrels" but they are called that because they fit a 7mm tube but actually measure .247". I'm not at home so I can't check to see if a 1/4" drill bit will fit through a bushing. Does anybody know or can check for me? Thanks in advance.

 

[dogcatcher]

The rods at Lowes and other stores "about" 1/4" in diameter, kind of hand grenade close, but not precision. Will it work, no clue, can it be made to work, yes. Chuck up a piece of the rod, and sand it down to size. Use ATF as a wetting agent for the sandpaper, measure often, remember to keep the sandpaper moving up and down the rod to be consistent.

 

[gtriever]

Yep, it works. I checked it with a Sierra bushing and a piece of 1/4-20 all-thread from my local True Value.

 

[ramaroodle]

That's what I figured. Either it would fit or I can sand/grind it to fit.

Thank you both very much.

 

[Sylvanite]

Yep, it works. I checked it with a Sierra bushing and a piece of 1/4-20 all-thread from my local True Value.

1/4-20 threaded rod is not really 1/4" in diameter. In actuality, it is slightly less than 1/4".

A 7mm brass tube won't slip over a true 1/4" solid rod - 7mm mandrels are made from letter D diameter rod.

That said, I have made several jigs for 7mm tubes using 1/4-20 threaded rod.

I hope that helps,
Eric

 

[ramaroodle]

Yep, it works. I checked it with a Sierra bushing and a piece of 1/4-20 all-thread from my local True Value.

1/4-20 threaded rod is not really 1/4" in diameter. In actuality, it is slightly less than 1/4".

A 7mm brass tube won't slip over a true 1/4" solid rod - 7mm mandrels are made from letter D diameter rod.

That said, I have made several jigs for 7mm tubes using 1/4-20 threaded rod.

I hope that helps,
Eric

Yes, that absolutely helps. Good to know. Thanks. The devil is always in the details. I was gonna get the threaded rod in addition to the 1/4" rod anyway so you saved me $6.