[Nethergate]

This might seem like an open ended question, I’m building a fixture table, what do people prefer, to use tapped holes and bolts in the top or tight fitting pins?

My problem is i cheaped out and only have a 6mm top and I’m worried that if I thread the holes it will only have a couple of theads at that thickness even with 10mm holes.

But I don’t like the idea of pins, but it does seem popular.

Any advice would help

Thanks James


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[dudley]

With only a 6mm top for the table you don't have much thickness to work with.

The question that comes to my mind is what type of clamps are you hoping to use on the table?
Just tapping holes in thinner plate like this wouldn't seem to work well in my opinion.

https://weldtables.com/products/fbn-1-f ... 8-16-t-nut

If you can produce accurate enough 16mm holes, the nuts in the link above might be a good option for using 3/8" hardware-- assuming you have clearance underneath to access the bottom of the table top.

There are clamps available for 16 mm holes in the certi-flat line of welding tables and tops which are only 3/16" thick steel (4.7mm). Not sure if they ship to Australia though.
https://weldtables.com/collections/clam ... xed-throat

[Coldman]

You haven't built the table yet so you still have the opportunity to uncheapout and get a decent top plate.
Building a fixture table is a lot of work, why go through with it and then curse the crappy 6mm top for the rest of your life?

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[Nethergate]

Thanks Dudley they look good but might get costly over 70 holes. I was toying with pilot drilling all my holes, cutting up 30mm bar stock and welding it under the table where my holes are going to go and then drill and tap


Coleman I’m only a a hobbyist and have a low budget for this stuff, the 6mm top cost me enough, I’m not worried about warping because I’m going to brace the bottom with 40 x 6 flat bar it’s just these holes that was stressing me.

Thanks for the advice guys


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[cj737]

A 1/4” (6mm) tip is sufficient for a fixture and welding table. You will only get so much accuracy and flatness out of it due to a lack of rigidity. No big deal if you’re a hobbyist.

I prefer 16mm holes. More options for tooling, clamps, and spacers.

[Nethergate]

A 1/4” (6mm) tip is sufficient for a fixture and welding table. You will only get so much accuracy and flatness out of it due to a lack of rigidity. No big deal if you’re a hobbyist.

I prefer 16mm holes. More options for tooling, clamps, and spacers.

I wasn’t worried about rigidity too much, I’ve got 6x40 flat bar which I’m going to put in a 200mm x 200mm grid under the top to brace it. The only reason I didn’t want 16mm holes is because on a 6mm top it will only bite a thread or two, but if I put pucks of bar stock under each hole it should be fine.

Thanks for the advice


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[dudley]

I wasn’t worried about rigidity too much, I’ve got 6x40 flat bar which I’m going to put in a 200mm x 200mm grid under the top to brace it. The only reason I didn’t want 16mm holes is because on a 6mm top it will only bite a thread or two, but if I put pucks of bar stock under each hole it should be fine.

Thanks for the advice


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To be clear, when I recommended 16 mm holes, they were thru holes with no threads.
All the standard type clamps and available 16 mm hardware I'm aware of uses a non-threaded hole .

If you're going to tap the plate, a much smaller diameter would be better.

- dudley

[Nethergate]

Hey guys, I’m in need of a bit of advice, in the end of my fixture table I wanted to make a slide out fence so I can extend the table out further or drop in some
Timber to try and double it as a table saw or plasma table etc.

I bought some steel which sleeves my shs and I can get it to slide in about 300mm then it gets stuck so I’m guessing one of the tubes isn’t 100% straight, I’m thinking of getting a belt sander and attacking the inner rail so it fits, it’s so close, I can use a sledge hammer to knock it in and out but of course that’s not ideal.

is there any better method of taking a millimetre or two off a 2m piece of steel or is the belt sander my best weapon of choice, main reason for the question is I’m about to buy a belt sander to do it but if it’s a waste of time I’ll just cut my losses and buy shs 5mm smaller


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[BugHunter]

If it warped slightly when welding, can you weld the other side to help straighten it back up?

I recently fixed a square tube cart here at work which had one of the rails bent by someone hitting it with a forklift. It also had an aluminum slide-out part that of course couldn't go in when it was bent. The square tubing was 2" (about 50mm) and the part that slid inside was about 1-3/4" (~45mm). Roughly a meter in length so there wasn't much room for error. I used a Harbor Freight porta-power along with some solid steel pieces inside the tubing as a mandrel and a 2-1/2 pound hand sledge. It took some effort, but I got it straight again. The trick is to not collapse the tube, or in my case, have some parts you can use to open it back up.

Obviously you need the hydraulic ram to push against something that isn't going to move. I used the frame of the cart in my case. With a mix of gentle and forceful, you might be surprised how easily a piece of tubing will move.

[cj737]

Hey guys, I’m in need of a bit of advice, in the end of my fixture table I wanted to make a slide out fence so I can extend the table out further or drop in some

I bought some steel which sleeves my shs and I can get it to slide in about 300mm then it gets stuck so I’m guessing one of the tubes isn’t 100% straight, I’m thinking of getting a belt sander and attacking the inner rail so it fits, it’s so close, I can use a sledge hammer to knock it in and out but of course that’s not ideal.

Is your hollow tube welded tube steel? If so, the weld may have some internal burrs that need removal. There are a few DIY tools for internal shearing of that welded seam. https://www.youtube.com/watch?v=3jr4Capx8XI&t=487s

If that is your problem...

[Nethergate]

Yeh that’s kind of my problem but my tube is 1800mm long so I can’t get anything down to deberr, which is why I tried smashing the inner tube down with the sledge hammer.

the other issue is the outer tube was factory seconds and isn’t folded completely square where the seam is, which is why I was going to try and sand down the inner tube which would be hard to do consistently with a grinder

Thanks for the reply


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[kiwi2wheels]

Is your hollow tube welded tube steel? If so, the weld may have some internal burrs that need removal. There are a few DIY tools for internal shearing of that welded seam. https://www.youtube.com/watch?v=3jr4Capx8XI&t=487s

If that is your problem...

Great link, thanks for posting

[Nethergate]

Thanks cj737, I’m an idiot and didn’t watch the whole
Video, that’s an awesome idea, defiantly going to give it a try


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[Nethergate]

I tried it, it got rid of the burr really well, but the tube still doesn’t fit, I’m thing it’s warped from factory because there is minimal welding to it, I might try the belt sander coz I won’t really want to go the next size tube down for the Inner, it’s 5mm smaller


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[cj737]

Well at least you tried and it helped some. Nothing wrong with a bit of sanding to ease the tolerances.

[BugHunter]

I tried it, it got rid of the burr really well, but the tube still doesn’t fit, I’m thing it’s warped from factory because there is minimal welding to it, I might try the belt sander coz I won’t really want to go the next size tube down for the Inner, it’s 5mm smaller


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If you don't have a good straight edge to check it, it's almost impossible to say it's straight enough. Also, ANY amount of welding absolutely bent the tube. No question about it.

For you to expect an almost 2M length steel part to telescope, and to do so with a relatively close fit, that's asking a lot.

[Coldman]

A belt sander will take ages to remove enough thickness. A grinding disc will be much faster. Even flat discs will be faster.

[Nethergate]

Yeh fair enough, anyone want to lend me their timber thicknesser in a totally unrelated matter haha


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[cj737]

Yeh fair enough, anyone want to lend me their timber thicknesser in a totally unrelated matter haha

Package it up and send it along. I'll run a face mill over it for you, free of charge. Of course shipping will cost you nearly $3,000 AUD

[Nethergate]

Hahaha thanks for the offer, might be more economical to start over


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[Nethergate]

So I had a play last night, I took a bit of bark off it and it fits better but still not great, the tube is not great as I said, I’m confident it’s not distortion due to heat, I tried it with a few off cuts, some fit some don’t and some you can just see they are out of square



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[Nethergate]

Double post sorry

[Coldman]

That's nasty tube

[Nethergate]

Yeh I got it off a guy who seems to have an endless supply on Facebook marketplace, they only come in 2400 lengths so I’m guessing they are factory seconds cut up so they aren’t so noticeable they are stuffed


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[Coldman]

Sounds like he's trying to make steel sales profit from scrap.
Sorry to tell you this but it will be very difficult to get a flat surface framing with that scrap. You should reconsider boning up for some good steel stock. You can use the scrap for a steel rack or something not dimensionally critical.
You want your table to be as good as you can get.