Large holes

[marcros]

I am looking at outsourcing some work, but before doing so would like to understand the likely process. The background is a batch production of 20 units, each unit having a hole in each end.

Material would be mild steel bar, 1/2" X 2 1/2".

How would a 2" hole be put into the bar? Is it as simple as a holesaw?

 

[Rorschach]

How accurate do they need to be?
A decent drill press will put a (good quality) 2" holesaw through that size of bar, it will be slow though, it also will not be super accurate.

You could get it CNC plasma cut at that thickness, probably tighter accuracy than the holesaw.

Best accuracy would be to have it plasma cut undersize and then bored out on a milling machine.

 

[TFrench]

How far in from the end is the hole? Room to get a V-block either side of it I assume? If I was doing it I think I'd do them slightly undersize on the radial arm drill then bore to size in the mill if they need to be super accurate. If I had the big mill running I'd do it all in that. I recently got some U-drills in a job lot I can't wait to have a go with - not sure if they go as big as 50mm though.
Edit - could also be a perfect job for a 50mm annular (rotabroach) cutter.

 

[Inspector]

A CNC mill can cut the holes by interpolation. A smaller bit spiraling in to remove the waste.

Pete

 

[marcros]

thanks everybody. good to get some options, before I get a price for fabrication of the parts.

 

[sunnybob]

I would seriously consider using tubing, and just block one end with a screwed or welded plug

 

[marcros]

the holes in tubes are in the wrong axis

 

[CHJ]

…..
Material would be mild steel bar, 1/2" X 2 1/2".
.

If the project requires the strength/stiffness of a 1/2" X 2 1/2", I query the advisability in cutting a 2" hole in the ends, there is only going to be 1/4" land each side which is a relatively weak point if any tension or bending loads are present.

On a small batch like that in an old style machine shop I would have used a vertical mill, drilled/endmilled and boring head to finish if size critcal.

If the holes are just for welding to 2" tubing the critical dimensions are not required (no boring head) and side wall becomes irrelevant.

 

[Phil Pascoe]

mild steel bar, 1/2" X 2 1/2".

I can't be the only person reading that as a two and a half inch length of half inch bar, can I? :?

 

[CHJ]

mild steel bar, 1/2" X 2 1/2".

I can't be the only person reading that as a two and a half inch length of half inch bar, can I? :?

With a 2" hole in each end??

 

[Phil Pascoe]

I know. That's what I found confusing. I then thought it was a two inch hole in a half inch long piece of two and a half inch bar.

 

[marcros]

this is what we are looking at having made https://www.fishleighandsonshop.co.uk/t ... -432-p.asp

but the ball ends that we need are in a virtually unobtainable size, and are only available as a part like https://www.agrilineproducts.com/parts- ... cat-1.html

the bar size is an estimate at the moment, pending getting some full measurements. it is a paperwork exercise to see whether it would be viable. There is a small demand for the parts, because originals are few and far between and there are no reproductions available at the moment. The tractors date from the 50's to early 60's, so mass manufacture is never going to be worthwhile.

 

[CHJ]

Are you sure that the originals are just 'Mild Steel'.

I've modified and repaired several 'linkage' components in a hurry to keep harvesting going to finish a task and some were certainly a much higher spec steel.

 

[marcros]

Are you sure that the originals are just 'Mild Steel'.

I've modified and repaired several 'linkage' components in a hurry to keep harvesting going to finish a task and some were certainly a much higher spec steel.

no, that was just a guess, more as background to the holes. they are on a garden tractor rather than anything lifting tonnes of weight, but it needs some more research.

 

[nev]

I'd suggest that the link arms are not a flat bar with holes in, rather a flat bar with the ball ends (or ball end holders welded on the ends) . given that the ball ends would have to welded into the holes anyway as if they were pressed into the two inch hole, as mentioned earlier, you have the entire load resting on the remaining quarter inch.
so your shopping list would then be flat bar at x length , 2 to 3 inch sections of flat bar with one side chamfered at an angle and the other side 2" concave to accept ball end units.
Of course I could be completely off the mark

 

[CHJ]

Basically the difference between the original forged/welded? 'Fergy' links and the Fordson ? welded retaining plate copy.

Or is my memory too far out, it's a long while since I struggled to lift gear into place on those link arms, I always seemed to be just at few inches out of alignment when trying to hitch them up.

 

[sunnybob]

The original sizes posted were why suggested tube. Something is wrong on that post, but the picture and explanation completely rules out mild steel in any shape or form.

There has to be another track rod end that would be longer, then it would just be a case of cut and shut. Or shorter, and just an extension welded in. At the cut stage the ball end orientation could be moved to fit the new application.

 

[Inspector]

Look for "link arm weld on ends" or a variation. I found this place with a quick search. https://www.tractorfactory.co.uk/ProductSection/107/ Then you only need to cut the steel bar stock to length and weld them. They are cheap and you can loose the entire hole making operation, saving a lot of time and money.

Pete

 

[marcros]

Pete, that was the first thought, but I cannot find any in cat 0 size.

 

[Inspector]

This eBay UK seller has Cat 1 but down the page they mention all the Cat sizes including 0. Get ahold of them and see if they have 0 in stock. https://www.ebay.co.uk/itm/Tractor-Lowe ... 3497911420

Pete