Hemingway Myford Top Slide Question

[Nicholas HillParticipant @nicholashill23289]

Hello, i am working on the Hemingway Kit of the Myford Top Slide. Most is self explanatory, but i am confused by Item 4.

I don’t see how it should work! According to the drawings, it is supposed to be 3/8 wide. However, it has 25/64 holes drilled through! So how does a 24/64 strip work with 25/64 holes in??

Am I completely missing something?

Many thanks, Nicholas

[ChrisLHParticipant @chrislh]

Standard Myford tee bolts are 5/16 BSF so perhaps J A Radford used these or something similar when constructing his new topslide but lost sight of the fact when doing his drawings ? Even with 5/16 holes through the key, only 1/32 a side thickness is not comfortable. Drawings in JAR’s book show the same conundrum by the way.

[Frank GorseParticipant @frankgorse]

Surely the 25/64” means a spotfacing dimension,though the drawing clearly says ‘thru’ ?

The through hole need only be clearance for whatever tee slot bolts you use.

[duncan webster 1Participant @duncanwebster1]

The dotted lines indicate the size of the slot into which the tenon fits, so not a problem. However, when you fit the tenon, the 25/64 hole is blanked off, no idea what is going on there

[BazParticipant @baz89810]

I don’t see the problem, the tenon will end up in thee pieces each piece secured by a M4 caphead. If it were mine I would just make the tenon in thee separate pieces stopping about 1mm short of whatever size hole you put in for your T bolts.

[halfnutParticipant @halfnut]

I checked my original JA Radford book. His drawings are a mish mash of misinformation on Part 4 and the mating T bolts that fit through those alleged 25/64 holes.

He specs the T bolts as 3/16 Whit, which is clearly too small. The matching nuts are called out as 5/16 Whit, which matches standard Myford size. Then he specs 3/8 clearance (25/64) holes through the body and the key Part 4, which are clearly oversize.

I would make your T bolts 5/16 and drill the four holes through the body and the key Part 4 for 5/16 clearance, ie 21/64. Yes the key Part 4 will be very thin around the holes but the 3 small screws will secure it. Drill it in situ.

If you have already drilled those whopping wrongly specced 25/64 holes through the body, 4 stout top hat shaped washers under the 4 nuts will tidy up the gap around your 5/16:T bolts.

Shame today’s suppliers don’t bother to supply a sheet of errata with these old drawings that often contain such errors that must have been discovered decades ago.

Nice project though. Keeps the topslide out the way of the dratted tailstock!

 

[Andrew CrowParticipant @andrewcrow91475]

Hi Nicholas, assuming that you haven’t yet drilled the 25/64 holes, just ignore the drawing and make them 17/64 or 21/64 to clear 1/4 or 5/16 bsf.

Considering the top slide on the ML7 was held by only two 1/4 bsf bolts I don’t think you will experience any problems when using four bolts of that size, you would probably be  OK using M6 if that’s more convenient for you.

Andy

[halfnut]

On halfnut Said:

I checked my original JA Radford book. His drawings are a mish mash of misinformation on Part 4 and the mating T bolts that fit through those alleged 25/64 holes.

He specs the T bolts as 3/16 Whit, which is clearly too small. The matching nuts are called out as 5/16 Whit, which matches standard Myford size. Then he specs 3/8 clearance (25/64) holes through the body and the key Part 4, which are clearly oversize.

I would make your T bolts 5/16 and drill the four holes through the body and the key Part 4 for 5/16 clearance, ie 21/64. Yes the key Part 4 will be very thin around the holes but the 3 small screws will secure it. Drill it in situ.

If you have already drilled those whopping wrongly specced 25/64 holes through the body, 4 stout top hat shaped washers under the 4 nuts will tidy up the gap around your 5/16:T bolts.

Shame today’s suppliers don’t bother to supply a sheet of errata with these old drawings that often contain such errors that must have been discovered decades ago.

Nice project though. Keeps the topslide out the way of the dratted tailstock!

 

Let me correct my earlier post after carefully reading the “words and music” in Radford’s original text.

Turns out 25/64  holes are correct. He advises to hold the key  (Part 4  in your updated partly metrically drawing) in place with the 3 small screws. Then drill through from the body. He says the key will be cit into 3 sections by this  but the 3 screws will hold each section secure.

He says in the text to make the T bolts 3/8 Whit. The nuts , he says, should be tapped 3/8 Whit but the hexagons should be made to the normal dimension for a 5/16 Whit nut, IE .525 AF.

So his original drawing contains only 1 error. That is the T bolts should be 3/8 Whit and not the 3/16 shown on his drawing.

Drawing and relevant text shown below in part as allowed under the fair useage provision of the copyright act for purpose of education and or journalism. The relevant text is bottom of first column and top of second.

[duncan webster 1Participant @duncanwebster1]

According to https://www.model-engineer.co.uk/forums/topic/ml7-top-slide-t-nuts-and-screws/

the bolts holding the topslide to the cross slide on an ml7 are 1/4 bsf. I reckon the Radford version which also has a tenon would manage quite well with the same, or metric equivalent. I never had thd top slide slip on my ml7

[Michael GilliganParticipant @michaelgilligan61133]

Just to confirm halfnut’s assertion … here, with due credit to hemingwaykits is a grab from their photograph:

.

.

It is abundantly clear that the fixings are as-described AND that the top-slide is for the Super7 not the ML7

MichaelG.

[Author]

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