Selection of Straight Edges in need of resurfacing - no suitable referance to start

Lurk · Jun 13, 2018

Appreciate this question will have been answered many times indirectly - (I'm still reading threads).

I have acquired a selection of cast Iron Straight Edges (4 @ 6ft) 1 @ 5ft, 1 @ 4ft & 2@ c3ft - widths vary from 2" to 4" ( & a good 2ft in proven condition) I have a 18x24" granite in good condition.

The older SE working faces were all badly rusted up and whilst they show some signs of scraping approx 30- 40% of the faces are pitted and lost.
I have need of a 6ft SE to begin my Hollbrook lathe refurbishment.

My question is what would be the most efficient/ effective way to re-scrape the working faces of the SEs so that I can put them to good use ?
I had imagined working the 6ft units to each other to 'average them out', and then use these as reference for the shorter SEs - that however has now taken a knock having read the thread earlier this year about the Whitworth 3 plate method (Forrest Addy write up) - I should really read these threads more frequently !
I appreciate that I could use the 2ft good SE and overlap it (6") working my way along and maybe do the 3ft first to then repeat the exercise on a 4ft, then 5 ft and finally 6ft ? i suspect the possibility of error building up this would be a less sure method.

Any advise greatly received

Hbjj · Jun 13, 2018

Is there a section of way on your lathe that you can use?
It would would never be as good as a plate but with careful use of your 2'se and a level and a king way type tool I would think you could get a 6'section of way within .001

johansen · Jun 13, 2018

Why not use the 4, 6' SE's and average them?

The issue with using a shorter se to make a longer one is the error is squared.

If you have a 2' se that is out by a tenth, the best you could make a 4' se would be convex or concave by 4 tenths.

So if you use the 2 to make a 3 foot, then use the 3 to make the 4, you need another 3 or 4 foot unit to correct the two longer units to eachother.

So what im saying is its going to take less time using the three plate method to scrape the 4 6'ers, then use them as masters to do all the others.

Or just buy a 6' granite se and when you're done sell it

Lurk · Jun 13, 2018

johansen - thats what I was thinking with respect the errors. Cant afford the 6ft granite even short term.

Hbjj - as far as the lathe bed goes - the only possible section not worn is badly mauled (shes not had an easy life by the looks of her.)
mat

Milland · Jun 13, 2018

Lurk said:
johansen - thats what I was thinking with respect the errors. Cant afford the 6ft granite even short term.

Hbjj - as far as the lathe bed goes - the only possible section not worn is badly mauled (shes not had an easy life by the looks of her.)
mat

Johansen has it right, take the four 6' (or best three of them) and do the classic rotation spotting/scraping against each other until you have three (or four) good references, then use those for the remaining edges. Be sure to support whichever is the base for the moment well, such that it's not bending or twisted by gravity or clamps.

If the pitting is really bad and you want it gone you may want to mill or plane them first, but it might be easier to put up with some small voids rather than find a place to cut them first.

Lurk · Jun 13, 2018

Milland said:
Johansen has it right, take the four 6' (or best three of them) and do the classic rotation spotting/scraping against each other until you have three (or four) good references, then use those for the remaining edges. Be sure to support whichever is the base for the moment well, such that it's not bending or twisted by gravity or clamps.

If the pitting is really bad and you want it gone you may want to mill or plane them first, but it might be easier to put up with some small voids rather than find a place to cut them first.

I can put up with pitting as long as the surface is useable. I think as things stand, averaging out the best three 6ft SE with similar widths is my best bet. It will make for a good upper body work out and get my scraping muscles back into practice.
mat

Richard King · Jun 13, 2018

I Googled Peak District and see your near Manchester. Member Tyrone who is a retired machine rebuilder is in Manchester and with his connections I bet he can find someone with a good granite table so you can test for the best 6' SE and make a stand so you can use that as a surface plate to do the rest. I see your near Shiefield too, there must be a machine shop or machine rebuilder near you that could help too. If not do the 3 plate method. Rich

PS: I asked Demon and Tyrone to comment...2 of our UK rebuilders :-) asked Mark Rand too, but his mailbox is full

Tyrone Shoelaces · Jun 13, 2018

Sorry Rich, Since I retired I'm out of the loop regarding getting favours from customers these days. The guy I could have relied on and who owed me plenty of favours retired and shut his shop earlier this year. He had a 10ft by 6ft by 1ft granite inspection table that I installed for him.

Regards Tyrone.

Lurk · Jun 13, 2018

Tyrone Shoelaces said:
Sorry Rich, Since I retired I'm out of the loop regarding getting favours from customers these days. The guy I could have relied on and who owed me plenty of favours retired and shut his shop earlier this year. He had a 10ft by 6ft by 1ft granite inspection table that I installed for him.

Regards Tyrone.

The SE's are from a friend that was a machine re-builder (served his time at Cravens bros Manchester) he is semi retired in his 70's now. Many of his former clients are no longer in business and the surface plates they had long since gone - what we are recovering now are the items he purchased over the years as firms shut & sold up and he stored in old units (thus the rust). If you ever pass my way Tyrone I would welcome the chance to meet you - I am between Stockport & Buxton.
cheers
Mat

Hbjj · Jun 13, 2018

So how will you measure the twist in your straight edges?

Lurk · Jun 13, 2018

Thats a good question.
I have a couple of machinist levels good to 0.0005/10" which would be a start sat accross the width of the face. I am thinking the 3 plate 'averaging' will high light any issues and allow me to remove twist / warp. It a lot of work though especially with the heavier versions - the largest SE is approx' 65kg so thats sitting on its back while others are moved over it ! I guess much will become clear when I take the first rubs off 3 of the SE's

Mark Rand · Jun 13, 2018

Sorry about the full inbox :drool5:

.

I've got a 4 foot granite straight edge that I won't need until I re-do my surface grinder starting next year. It was grade 0 before I ever saw it, but I don't yet know how good it is now, since I haven't yet set up to use my autocollimator to check it. Plan was to re-lap my 3'x4' surface table and the straight edge to grade 0 before re-scraping the surface grinder.

I'm about a hundred miles south south-east of 'between Stockport and Buxton' in Rugby.

If you are happy to scrape three straight edges against each other to get straightness in a modified Whitworth technique, you can correct for flatness by using a precision level across the straight edges to detect changes in tilt along their length. If the Holbrook is one of the less ancient ones that's got a V and flat type bed, then you really need to use a level in a 'King Way' type device to make sure that the inverted V and the flat parts of the way are parallel with each other. Have you got or are you up to making such a level or kingway jig? I might have a spare 0.2 thou in 10" level vial somewhere that you could have for about £25!

Edit to add:- I must have taken a long time to type this, If you are set with the levels, you can do the straight edges! A crane or hoist, even one of the engine hoist things can be your friend when handling them...

Milland · Jun 13, 2018

Lurk said:
Thats a good question.
I have a couple of machinist levels good to 0.0005/10" which would be a start sat accross the width of the face. I am thinking the 3 plate 'averaging' will high light any issues and allow me to remove twist / warp. It a lot of work though especially with the heavier versions - the largest SE is approx' 65kg so thats sitting on its back while others are moved over it ! I guess much will become clear when I take the first rubs off 3 of the SE's

At that weight, unless you're a muscular youngster perhaps setting up a pulley block (with some shock cords for a little give) over the bench might be kinder to one's back. Let's you handle the edge being worked on a little easier, without adding any warp effect once placed on the base edge.

Another thought - your friend who worked at Craven must have some good stories to tell. If there's any way you could feed him a few pints, plant him in front of a video camera, and get some of the tales on record that would be really interesting to many of us here. Even better if you can rope Tyrone into the deal.

In fact, I bet there's dozens of folks on this site who it would be great to get oral histories from, I could see it as a branch of the Antiques (sorry guys) sub, or it's own standalone section. What say you?

Richard King · Jun 13, 2018

Thanks Mark. Lurk you should take Mark up on his offer. So much easier to have a teacher showing you how then guessing and double guessing each step. On your drive done , pick up Tyrone and you will get 2 for the price of lunch I bet. :-)

Lurk · Jun 14, 2018

Mark Rand said:
Sorry about the full inbox .

I've got a 4 foot granite straight edge that I won't need until I re-do my surface grinder starting next year. It was grade 0 before I ever saw it, but I don't yet know how good it is now, since I haven't yet set up to use my autocollimator to check it. Plan was to re-lap my 3'x4' surface table and the straight edge to grade 0 before re-scraping the surface grinder.

I'm about a hundred miles south south-east of 'between Stockport and Buxton' in Rugby.

If you are happy to scrape three straight edges against each other to get straightness in a modified Whitworth technique, you can correct for flatness by using a precision level across the straight edges to detect changes in tilt along their length. If the Holbrook is one of the less ancient ones that's got a V and flat type bed, then you really need to use a level in a 'King Way' type device to make sure that the inverted V and the flat parts of the way are parallel with each other. Have you got or are you up to making such a level or kingway jig? I might have a spare 0.2 thou in 10" level vial somewhere that you could have for about £25!

Edit to add:- I must have taken a long time to type this, If you are set with the levels, you can do the straight edges! A crane or hoist, even one of the engine hoist things can be your friend when handling them...

Hi Mark, thanks for the reply, Rugby - not too far away. I am looking at making up some form of Kingway arrangement for the bed ways & cross slide etc. A dedicated Vial would be handy to build in for sure and its the more accurate unit than my half thou' levels 7 level squares. The Hollbrook dates from early 1950's twin Vs & flats on the bed and white metal main spindle bearings (also badly worn - but that's another thread later ;-)) Drop me a PM ref the vial. Thanks mat

Tyrone Shoelaces · Jun 14, 2018

Lurk said:
The SE's are from a friend that was a machine re-builder (served his time at Cravens bros Manchester) he is semi retired in his 70's now. Many of his former clients are no longer in business and the surface plates they had long since gone - what we are recovering now are the items he purchased over the years as firms shut & sold up and he stored in old units (thus the rust). If you ever pass my way Tyrone I would welcome the chance to meet you - I am between Stockport & Buxton.
cheers
Mat

Unfortunately your pal's story regarding the decline of the industry in his area is similar to mine. When I came out of my time in 1970 the Union ( AUEW ) used to produce a list of the wage rates of the Engineering Companies in my area. There must have been 30 companies on that list in 1970. This was just in my local area and only the larger companies that had Union representation.

Today there is about 3 or 4 of those still in business with 1 or 2 new companies setting up in their place.

They did a survey around that time ( 1970 )and in the Greater Rochdale area with the outlying smaller towns there were 30,000 people employed in Engineering and allied trades, foundry work, sheet metal work etc. A few years ago they did the same survey and it was less than 3,000 !

The places that I know that are still left and were big enough to have medium to large inspection tables I could count on the fingers of one hand and they all had their own maintenance teams so I never got work with them.

How places like " Craven " went out of business I'll never know. They were market leaders in the massive machine tool world. I suspect really bad management by the Staveley Group who took them over.

Regards Tyrone.

Lurk · Jun 14, 2018

Milland said:
At that weight, unless you're a muscular youngster perhaps setting up a pulley block (with some shock cords for a little give) over the bench might be kinder to one's back. Let's you handle the edge being worked on a little easier, without adding any warp effect once placed on the base edge.

Another thought - your friend who worked at Craven must have some good stories to tell. If there's any way you could feed him a few pints, plant him in front of a video camera, and get some of the tales on record that would be really interesting to many of us here. Even better if you can rope Tyrone into the deal.

In fact, I bet there's dozens of folks on this site who it would be great to get oral histories from, I could see it as a branch of the Antiques (sorry guys) sub, or it's own standalone section. What say you?

I have invested in a small 'action camera' with 32GB memory card for just this - in between re-telling his favorite tales a new one pops out - I plan to edit a few tales into each update of my progress with learning the skills and rebuilding the Hollbrook on my YT channel.
Good to hear that it sounds of interest to others and not just me ;-)
All the best Mat

Milland · Jun 14, 2018

Sounds great! Get Mark into that too, if you can. What's the channel?

Lurk · Jun 14, 2018

Milland said:
Sounds great! Get Mark into that too, if you can. What's the channel?

I will post a link once I have a video of the 'folk' chatting - might have to sensor the language as it can get quite colorful at times. My channel is Lookcreations - I recorded my shaper restoration last year - a steep learning curve on that, supported by this forum - the resulting machine is a joy to use. lookcreations
- YouTube
All the best Mat

johansen · Jun 14, 2018

The three plate method does not have a twist problem.

Selection of Straight Edges in need of resurfacing - no suitable referance to start

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