Has anyone ever wondered where the 28mm hole diameter originated from? Why was this diameter hole chosen? Frankly to me it’s a strange diameter to pick for a hole. There is no direct imperial size that is close. Trying to find a bolt that can be substituted for a pin is difficult to find. The minimum hole spacing between holes is 50mm. What shear loads were they looking for to require such a large diameter pin? Any thoughts?
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I’d be interested to hear why that was chosen as well. It does seem like an odd number to choose. You’d think they would have went with 25 or 30 instead of 28.
I’m pretty sure they did it so you don’t have an easy option to drill a 28mm hole or buy a regular hex bolt to fit the table. I speculate that they want you to buy the fixture and special sized bolts. I’ve never liked this concept of preventing someone from making their own fixtures or tools. This is one of reasons I went with the 3/4 table system. All the strength of the 28mm fixtures but with a hole that is easily drilled or bolts that you can find at the hardware store.
Im trying to remember a time that I needed a 28mm bolt to temporarily or permanently bolt something together.
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Before modern fixture tables there were the original fixture tables that supposedly have their origins tied to ship making, evolving into the platen tables with the square holes that preceded what is the standard round hole tables of today. It being 28mm would certainly lead one to think its roots are in Europe?! It’s definitely an odd number at least from our perspective! I’d assume they made them that big to contend with the standard equipment on the tables of that time. Size shows strength! The holes in the old tables are 1-1/2". if you compare that standard to a 3/4" clamp and blocks its laughable! It might be strong enough but looks very weak comparatively…
28mm may be odd but it’s the standard and many companies and individuals have a lot of investment in it, same with 16mm.
I think you made a mistake blazing your own trail in this market! If 3/4" is plenty strong as you say, then 16mm isn’t far off! It certainly comes down to more than shear strength! If you do a tug of war at the top of L squares on each table with their respective tooling, which is going to give first?
You could be making a lot more money selling your tooling if you make it 16, 22,28mm! You have great stuff but ostracizing everyone that is already in with other brands was a poor business decision imo.
I do sell the Fireball system fixtures in 5/8,16mm and 28mm. 16mm fixtures are puny compared the 3/4 fireball.
They aren’t even in the ball park. 3/4 is 50% more then the 16mm. Just look at the how much more material is left on the sides of the slotted fixture 28mm vs 3/4. The 3/4 fixtures are very strong. The Have you ever wondered why table companies make different tables and holes sizes? Why not one hole size that can do everything? They want you to buy a 16mm for smaller projects and 28mm for larger. Why aren’t you mad the them for making 3 different hole sizes? Most fabricators like myself do all sizes of projects depending on the day. Purchasing a table system is a big investment and choosing the wrong size could be expensive if it doesn’t meet the requirements for what you’re working on. The 3/4 system hits the sweet spot. Heavy duty fixtures like the 28mm but high hole resolution like the 5/8 and 16mm. It’s the best of both worlds.
I’m more than happy to sell you a table with 4” holes if it means it looks stronger. Fine by me less holes to drill.
The fireball fixture are the same size as the 28mm. The fireball fixtures are just as strong.
The reason for the 3/4 diameter is it allows for more hole resolution, shorter fixtures, lowering the cost of the tooling without any drawbacks. The higher resolution helps with small short parts or large projects. So this hole size is more suited for a fabricator that does more variety of projects.
Design a test and I’ll put both systems through it.
Let’s fixture small parts and large. I have every table in the workshop to do the test.
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I don’t much care for the 28mm system either! But it’s still the main standard. 22mm should be the flagship for all brands! The reason the 16mm fixtures are that small is because they made them small. You can make your fixtures the same size and just put 16mm slots and holes in them… next you’ll say is then the table isn’t strong enough! Then make it thicker! 3/4” has more material than 16mm, and 22mm has a lot more than 3/4”… How many people are breaking pins, even 16mm?
Is hole resolution a big deal!? Maybe, mostly for your toothed block, which is your best tool! I don’t see it working well for a 4” system. Otherwise 2” kinda makes for a bad workbench as you have more chance of dropping things through. Minor, but still annoying!
I see nothing but clamps for 28mm on your website, am I not looking in the right spot?
The problem with slotted fixtures is keeping them from turning. A good test would be to use the pin bolts and see which holds their position better, both with hand tightening and with wrench.
Another test would be how strong the pin bolts are from pulling free. I really can’t see any of them failing but the table or fixture might!? Put two different brand square fixtures face to face leaving room in between and a pin in the hole closest to the face and clamp them together and see which fails. Do it again with the bolts all the way back from the face. Seeing as your squares are two piece you’re at a disadvantage but still should be tested as it’s a practical situation as I’ve clamped pieces from up high and would like to know how much it bends and it’s breaking point.
Another valuable test would be how much clamping force you can generate throughout the range of the clamp, both in perpendicular and parallel. I my clamp can slip out of the hole a bit when it’s close, might be from a dirty hole🤷♂️ but still curious on how much force can be generated on these clamps.
What table system do you currently have?
Siegmund 22. I bought it last year at fabtech. I definitely like your tooling better but it came down to size of tables and selection of riser blocks. And for how I beat on everything I own I trust steel over cast. I don’t see any reason for you not to offer steel tables as well. Easy to source! The tooling is where the money is at!
Have you used a cast iron table to base your option on? There are cast iron tables that are over 100 year old still being used. Cast iron has many benefits that’s hard to get with steel.
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Just my gut instinct! So far I’m very impressed by how my Siegmund is holding up. Spatter hasn’t been an issue. I assume you don’t do grid lines because it’s cast? Grid lines are very helpful! When it comes down to it the differences are probably overstated… when are you going to post the video of the strength tests from a few months ago? Make a believer out of me!
Siegmund has a good table system. They have set the benchmark high. I do believe every design can be improved on, including our own designs, and that’s our goal at fireball. Our goal was to keep the table price as low as possible that’s why they don’t currently have a grid. There has been enough requests for the grid to offer it as a future option coming soon.
We’re working on the videos at the moment. Look for them in a few weeks.
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Thats what I most respect about you and your company, pushing innovation! The big established companies get complacent and put it on cruise control, that’s when they get passed.
I’m not trying to give you too much grief, I just want to keep you honest, you lose that, and you lose everything! I appreciate the videos and showing the differences and innovation behind your tools.
Now get going on tools for my 22! 
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Not sure where this will land but here goes:
Consider the difference between making your parts correctly (That is very close to their intended size and form) versus making them casually and trying to force them into shape before welding using fence blocks and the like.
Properly made parts fit. Casually made parts need to be persuaded. If you don’t need to persuade your parts you don’t need big, tough holes and pins.
There’s a lot more that could be said about locating parts on a fixture table without applying loads that affect the part’s shape but parts forced into shape before welding can distort a weldment in unpredictable ways. Parts that just fit? Not so much.
Ah old cast iron! I remember when engine castings were aged for months before being machined. They made some bullet-proof engines back then.