• We want to encourage those of you who ENJOY our site and find it USEFUL to DONATE and UPGRADE your membership from active member to donating or premium membership. If you want to know the differences in membership benefits, please visit THIS PAGE:

    https://www.hobby-machinist.com/premium/

    Donating memberships start at just $10 per year. These memberships are in fact donations that help pay our costs, and keep our site running!
    Thank you for your donation, God Bless You

[4]

I need to affix a fastener deep inside a tube

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#1
I am fabricating some leveling feet tubes that will reside under my Bridgeport clone (similar to the pic below, but 2in x 3in and thicker wall).

The leveling feet will be spaced a little wider apart than those in the pic to accommodate the forks on my pallet jack, consequently the rectangular tube will be longer.

I need to "attach" a fastener inside the tube in order to screw in the long 1/2-13 bolts circled in white. The 1/4 inch thick tube wall would not provide adequate thread engagement if I were to simply tap the hole.

I originally thought I would simply turn a shoulder on some standard nuts, carefully located them inside the tube, and weld them in place at the outside surface, but then I thought that this might anneal the nut ruining it's strength.

I can't simply run the bolt through both sides of the the tube and apply a nut on the far side because it needs to clear the forks on the pallet jack.

I'm not finding any nutsert type system for 1/2-13.

Now I'm thinking I may drill and tap some appropriately thick flat stock for 1/2-13 and "pin it" in place inside the tube for a no-weld solution.

I know I'm probably over thinking this but...

Can anyone offer some pears of wisdom, or an alternative approach?

Bridgeport_leveling_feet1_annotated.jpg
 

woodchucker

Titanium
Former Member
Joined
Nov 25, 2015
Messages
1,504
Likes
1,031
#2
I am fabricating some leveling feet tubes that will reside under my Bridgeport clone (similar to the pic below, but 2in x 3in and thicker wall).

The leveling feet will be spaced a little wider apart than those in the pic to accommodate the forks on my pallet jack, consequently the rectangular tube will be longer.

I need to "attach" a fastener inside the tube in order to screw in the long 1/2-13 bolts circled in white. The 1/4 inch thick tube wall would not provide adequate thread engagement if I were to simply tap the hole.

I originally thought I would simply turn a shoulder on some standard nuts, carefully located them inside the tube, and weld them in place at the outside surface, but then I thought that this might anneal the nut ruining it's strength.

I can't simply run the bolt through both sides of the the tube and apply a nut on the far side because it needs to clear the forks on the pallet jack.

I'm not finding any nutsert type system for 1/2-13.

Can anyone offer some pears of wisdom, or an alternative approach?

View attachment 265971
Why wouldn't you just thread the tube. Or drill through the tube and put the nut on the underside.
I would just thread the tube.
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#3
Why wouldn't you just thread the tube. Or drill through the tube and put the nut on the underside.
I would just thread the tube.
Not enough thread engagement (just 3 threads and well under the recommended) and it needs to clear the forks on my pallet jack on the underside.
 

682bear

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Nov 28, 2016
Messages
220
Likes
373
#4
I like your idea about a thicker piece of flat stock placed inside the tube, but instead of 'pinning' it, I would drill holes in the tube, locate the flat stock, and then 'plug weld' the stock to the tube... then locate the 1/2-13 holes and drill/tap with the flat stock in place.

FWIW, I have welded flange nuts in steel tube also...

-Bear
 

British Steel

Active User
Former Member
Joined
May 12, 2011
Messages
767
Likes
640
#5
Correct me if I'm wrong, but...

Won't the only tension load on the tube be if it's hanging from the mill? If the concern is with the tube trying to roll, plate welded at 90 to the tube should take care of it, the bolts wouldn't be under a great deal of stress and the machined-to-flange-nuts welded in would likely be several times as strong as you'd need...?

Personally, I'd run a piece of thick-walled tube right through the box section and weld both ends, drill and tap the upper end perhaps 1/2" deep minimum for the 1/2" bolt thread, but add the stabilising tabs anyway!

Dave H. (the other one)
 

David S

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 18, 2012
Messages
1,257
Likes
995
#6
Why not just a single piece of flat stock that runs the full length of the square tube. Drill and tap the flat stock on the same centres as the clearance holes in the tube under the mill. Then you should be able to hold everything in place from the ends and line it up and not have to worry about fiddly pieces way inside the tube.

David
 

ezduzit

Active User
Registered
Joined
Jul 19, 2013
Messages
370
Likes
158
#7
In a length of scrap wood, counterbore a hole just large enough to hold a 1/2-13 hex nut under the clearance hole. Make the clearance hole in the tube large enough so you can weld the nut to the tube. Chase with a tap after welding.
 

woodchucker

Titanium
Former Member
Joined
Nov 25, 2015
Messages
1,504
Likes
1,031
#8
I don't think there is any danger of annealing the nut. The nut is probably not hardened. Normal nuts are mild steel. Is this a graded nut?
Weld it to the top side, an you are done. If you are sure you need it graded, you can use cool air from a compressor to cool it quickly. It won't be full grade, but it won't be soft, and it won't warp the tube by cooling it way to fast in water or oil.
 

Nogoingback

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Oct 18, 2016
Messages
823
Likes
640
#11
Why not use square bar instead of tube and drill and tap that?
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#12
I like your idea about a thicker piece of flat stock placed inside the tube, but instead of 'pinning' it, I would drill holes in the tube, locate the flat stock, and then 'plug weld' the stock to the tube... then locate the 1/2-13 holes and drill/tap with the flat stock in place.

FWIW, I have welded flange nuts in steel tube also...

-Bear
Hi Bear

I like this idea.

I could pre-drill and tap the 1/2-13 holes in the flat stock, bolt it in place inside the tube for registration, and plug weld the two together. Remove the temporary bolt, and voila!

If the plug welds were far enough away from the threads there would be no HAZ issues.

The plug welds would basically be a "heavy tack" correct? How big should the holes for the plug weld be, practically speaking?
 

Nogoingback

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Oct 18, 2016
Messages
823
Likes
640
#14
What size tube were you planning on using? If you think a bar would flex, use a bigger bar!
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#15
My rectangular tube is 2in x 3in x 1/4in wall. It will be oriented flat for less tendency to roll when raising the mill (lowering the feet) to get the pallet jack under it.

Already had the materials when I learned of the flat stock approach.
 

682bear

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Nov 28, 2016
Messages
220
Likes
373
#16
Hi Bear

I like this idea.

I could pre-drill and tap the 1/2-13 holes in the flat stock, bolt it in place inside the tube for registration, and plug weld the two together. Remove the temporary bolt, and voila!

If the plug welds were far enough away from the threads there would be no HAZ issues.

The plug welds would basically be a "heavy tack" correct? How big should the holes for the plug weld be, practically speaking?
The size of the holes really wouldn't be important... as long as they are large enough to get a sufficent weld... probably 5/16 or 3/8 would be plenty.

The welds are only there to hold the bar in place until it is bolted to the bottom of the machine... after it is mounted, the welds serve no purpose at all.

-Bear
 

Asm109

Registered
Registered
Joined
Aug 29, 2017
Messages
187
Likes
204
#17
Take a chunk of 1 inch solid bar. Tap it for you screws. I assume you are using 1/2 inch.
Drill a 1 inch hole all the way thru the tubing.
Push the chunk of bar into the the tube and weld a circle on each side of the tube.
Done.
That's how I put bomb proof mounts in tubing on dune buggy frames.
 

GL

Registered
Registered
Joined
Aug 13, 2017
Messages
25
Likes
18
#18
Yep, don't worry about the nuts doing funny things when you weld on them. We build heavy duty commercial trucks and use weld nuts inside the frame to hold everything on - been doing it for years. Three heavy tacks will do fine. However, welding a nut inside a tube is going to be tricky without opening up a big clearance hole on the bottom side, which also kills your strength unless you cap over it when you get done. I like the big bar inside plug welded to the side of the tube idea. Plus that gives your feet something more substantial to rest on (if the bar sticks out that far). I agree that the feet thing looks wiggly - any vibrations are carried by 4 points, maybe four 1/2-13 bolts. The bolts in the tube through the base are not really doing much of anything structurally, more positionholder. Rule of thumb for plug welds: min diameter is 1.5 times material thickness for structural applications, let's you get some heat in the hole before you close it up.
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#19
OP here.

I might've gotten ahead of myself.

I am an amateur welder, with a Millermatic 211 mig welder (capacity 3/8in). Probably shouldn't expect a decent plug weld with a 1/2in thick bar stock and 1/4in tube wall.

I can take it to a real welder.
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#20
Duplicate deleted by author.
 
Last edited:

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#21
I agree that the feet thing looks wiggly - any vibrations are carried by 4 points, maybe four 1/2-13 bolts. The bolts in the tube through the base are not really doing much of anything structurally, more positionholder. Rule of thumb for plug welds: min diameter is 1.5 times material thickness for structural applications, let's you get some heat in the hole before you close it up.
The bolts through the base of the mill are 1/2-13.

The leveling feet assemblies have 5/8in diameter studs and are rated at 4500lbs capacity each. They will only be carrying 600lbs each statically. I think there is plenty of margin on the leveling feet.
 
Last edited:

David S

Active User
H-M Supporter - Gold Member ($25)
Joined
Nov 18, 2012
Messages
1,257
Likes
995
#22
Wow guys lots of neat ideas. I still think one long flat bar the length of the tube would be real easy and no welding required. It could be captured by the out rigger screws. May cost more though.

David
 

GL

Registered
Registered
Joined
Aug 13, 2017
Messages
25
Likes
18
#23
Woke up at 2a thinking about this. The whole plan is to raise the mill up so you can get a pallet jack under it. The wider is also to accommodate the width of the jack. What happens if you go sideways - since the mounting holes in the base of the mill are further apart front to rear than they are side to side. May be a space issue.

The other think I was thinking about was the hardware to hold the bars/tubes on. What happens if you use flathead bolts going from the bottom up. You will need some more meat than the tube will give you for the countersink on the bottom - so weld in a tube with the countersink on one end through a clearance hole on the bottom, nut on top. No tapping required. The down side may be that you have to lift the mill up far enough to get the bolt in the hole.

Lots of ways to skin the cat.
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#24
Woke up at 2a thinking about this. The whole plan is to raise the mill up so you can get a pallet jack under it. The wider is also to accommodate the width of the jack. What happens if you go sideways - since the mounting holes in the base of the mill are further apart front to rear than they are side to side. May be a space issue.
Glad you're thinking of me at 2am... I think! :)

Until now that's how I've been moving the mill is with the pallet jack from the side, but my mill has the lathe on one side and benches with toolboxes on the other. It's a major ordeal to make room for the pallet jack. From the front is the best solution for my situation.
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#25
I thought I may be on to something, but after working up scale CAD drawing it's a no go.

I thought I may be able to fish a standard nylock nut past the leveling foot stud with one of those curved wrenches, but no worky. A straight wrench definately won't work either.

Looks like some drilled and tapped flat stock plug welded is the most many way to go. :)


LEVELING_FEET_STUDY.jpg
 

Attachments

extropic

Active User
Former Member
Joined
Nov 24, 2014
Messages
533
Likes
353
#26
Drill the rectangular tube 1" diameter through both walls and weld, on both sides, a piece of 1" diameter steel rod through the tube. Grind flush on both faces, drill and tap to your hearts desire.
 

cg285

Registered
Registered
Joined
Jan 10, 2018
Messages
248
Likes
93
#27
i don't see why you don't just tap the existing holes, get tap bolts of the appropriate size, round the ends, cut some square plate, run a ball end mill in the middle of the plate to match the tap bolt, done.
 

woodchucker

Titanium
Former Member
Joined
Nov 25, 2015
Messages
1,504
Likes
1,031
#28
i don't see why you don't just tap the existing holes, get tap bolts of the appropriate size, round the ends, cut some square plate, run a ball end mill in the middle of the plate to match the tap bolt, done.
As he replied to me, he is only going to get 3 threads, and is concerned that won't be enough. maybe with a fine thread it might make it.
 

jmarkwolf

Active User
Registered
Joined
Nov 9, 2012
Messages
327
Likes
193
#29
As he replied to me, he is only going to get 3 threads, and is concerned that won't be enough. maybe with a fine thread it might make it.
Correct.

13 threads per inch (1/2-13 bolt) in 1/4in thick material is just 3 threads engagement.

I'm leaning heavily towards Bear's idea of plug welding an interior threaded plate.

I also like the idea of welding a round threaded "bushing" through the tube. My welder still doesn't have the capacity however.
 
[6]
[5] [7]
Top