123 blocks

Some while ago I bought some 123 blocks from RDG. These have been used for parallels, raising blocks etc up to now. The other day I needed to square up some Ally blocks and wanted to
bolt two blocks together to give me two vertical faces for the edge and side of the blocks, a couple of clamps to hold the ally and I should be ok. The blocks have tapped and clearance holes so should be a doddle to bolt them together with two 3/8" UNC capscrews.
NOPE the tapped holes are 3/8" UNC the clearance holes are 9mm. Queried it with RDG and told "they are not designed to be bolted together".
I am surprised, should I be?
Richard
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used
be
Yes I bought some ages ago (it was the SMEE centeniary exhib at Brunel iirc) - un wrapped them, found the same issue - thought 'that's stupid', wrapped them up again and they're still wrapped unused in a box somewhere. Daft isn't it!
AWEM
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This is a subject that has been covered on various forums before.
The outcome as far as I can remember is that some of the early American patterns did have clearance holes. It seems that the problem occurred when Starrett had some done off shore and they put the smaller hole in.
In usual third world style everybody copied everyone else and we finished up with a new Taiwanese [ the Chinese hadn't got involved at this point ] standard. The problem is we are now stuck with this unless someone insists they move the goalposts. The problem is there are so many companies making these as they are easy to make that we may never manage to get back to a working standard.
It took ages for the fiasco with the R8 taper when Grizzly sent a bad taper over to China and they were making everything to fit this taper with the result that we were seeing spindles with the top diameter too tight and the keyways too shallow. This has just about got resolved but occasionally a new guy on the block buys up old stock and moves it on.
John s.
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On Sun, 14 Dec 2008 18:51:59 -0000, "Andrew Mawson"

I did manage to open up two holes to clear the screws using a "modified" 10mm masonary drill. Also made some 8mm tapped Tee nuts so that I could clamp them to the table with studding. I did therefore achieve what I set out to do. Based on John S's comments it appears that RDG's "they are not designed to be bolted together". Should really read "someone at some time in the dim and distant past screwed up and we are not bothered!!"
Richard
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Perhaps they were intended to fasten together with a short all-thread stud so that the opposing faces would be clear. Of course the other faces would not likely align but that might not matter if you were stacking blocks for some reason. Ideal would seem to be RH and LH threads on opposing sides and a corresponding hollow stud tightened with a long hex wrench through the hole.
Don Young
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On Sun, 14 Dec 2008 20:34:12 -0600, Don Young wrote:

Neither of those approaches would work if there was any need to have the blocks at any particular orientation (to each other) as the threads on both blocks and the studs or all-thread would only permit one random alignment when the all-thread/stud drew them tight.
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On Mon, 15 Dec 2008 02:41:07 GMT, _

You might be ashamed of your name, but it's polite to announce who you are anyway :-|
Mark Rand RTFM
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On Mon, 15 Dec 2008 04:43:48 +0000, Mark Rand wrote:

There are things in usenet posts you may not be seeing; they are called "headers". If you RTFM for your newsreader you can figure out how to see them.
As for notions of what is polite in usenet - you must be a relative newcomer...
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On Tue, 16 Dec 2008 09:30:28 GMT, _

I'm well aware of your munged email address. However, you are not bothering with announcing your name with your posts and are not signing a name. That is not polite.
As to being a relative newcomer, yes that is probably the case. I've only been using Usenet for the last twenty years.
Mark Rand RTFM
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wrote:

Nicely put, Mark. Our anonymous friend has probably had his fingers burned on other newsgroups and may not be aware of the more polite conventions here. It's his loss I'm afraid as I don't reply to anonymous messages.
Cliff Coggin.
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On or around Tue, 16 Dec 2008 17:45:43 -0000, "Cliff Coggin"

There are indeed less salubrious areas in usenet, but on the whole, I agree. My name is in the public domain and I see no reason to conceal it on usenet. I'm a good deal more wary about addresses, although anyone who seriously wanted to find me wouldn't have that much trouble.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
  Click to see the full signature.
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And once they had done that some judicious investigations on Dejanews would tell them what van to nick before paying a visit...
--
Boo

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Richard Edwards wrote:

Please clarify (for the ignorant, to whit, me).
Do I assume 3/8" UNC needs more than 9mm clearance?
BugBear
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On Mon, 15 Dec 2008 16:40:42 +0000, bugbear

3/8 x 25.4 = 9.525mm so yes you assume correctly.
I called the non tapped "clearance" holes as that is what I incorrectly assumed they would be. Silly thing is they are not even tap drill size for the tapped holes so someone actually changed drills to be able to drill them incorrectly. The blocks are hard so it is somewhat difficult to open them up, though did manage on two holes.
Richard
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Richard Edwards wrote:

So the only way to use them "as envisaged" would be to use a thread reducer (e.g. reduce 3/8" to 1/4") in the threaded part, such that (e.g.) 1/4" OD would pass?
BugBear
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a thought which just occured to me: use a solid carbide spade type tile drill to open the holes out. such as http://tinyurl.com/6mq3cq - 10mm
Dave
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On Mon, 15 Dec 2008 11:34:42 -0800 (PST), dave sanderson

As I mentioned in a previous post I used a masonary drill which I ground to a cutting edge as opposed to a percussion edge. A tile drill could be better. Main problem is breaking past the cross holes where the drill jams. I drilled from both sides and finished off the middle with a "Dremeloid".
Richard
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The advantage of a tile drill is the progressive widening of the hole due to the pointy nature of the shape. the spade gives good clearance for coolant too :) I had to modify a hardened chinese AXA style tool holder not so long ago, that was also very hard, they got the heat treat on the block spot on, shame about the cheese related screws :(
Dave
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