this is more metrology then reconditioning, but i need to make a tool for alignment

dcsipo · Sep 16, 2017

Hi

i need to to make one of these....

12'x x 6' 1"+ depending what cast iron piece i get a hold of.

the front edge 45[SUP]o[/SUP] I will scrape it on all sides. The question comes in, how do i measure the 45[SUP]o[/SUP] on the front to make sure they are perfectly centered and truly 45[SUP]o[/SUP] and parallel to the back. I have a 3" wide 5" sine bar, i think i can balance it on it and set it at 45[SUP]o[/SUP], but i see too many potential errors creeping in. I have a pair of B&S V blocks i could qualify them first and use them but they only have a 2.5" sloping side. I would like to get the whole thing within 2 thenths overall. i know i can scrape to that, but not certain i can measure to that with my setups. Anybody have some oldtimer tricks up their sleeves?

dee
;-D

Milland · Sep 16, 2017

dcsipo said:
Hi

i need to to make one of these....

12'x x 6' 1"+ depending what cast iron piece i get a hold of.

View attachment 208036

the front edge 45[SUP]o[/SUP] I will scrape it on all sides. The question comes in, how do i measure the 45[SUP]o[/SUP] on the front to make sure they are perfectly centered and truly 45[SUP]o[/SUP and parallel to the back. I have a 3" wide 5" sine bar, i think i can balance it on it and set it at 45[SUP]o[/SUP, but i see too many potential errors creeping in. I have a pair of B&S V blocks i could qualify them first and use them but they only have a 2.5" sloping side. I would like to get the whole thing within 2 thenths overall. i know i can scrape to that, but not certain i can measure to that with my setups. Anybody have some oldtimer tricks up their sleeves?

dee
;-D

Not an oldtimer (yet), but something that comes to mind is a narrower second plate of the same thickness, with four precision pins bedded in the plate such that when they're flat on a plate they mate at tangency. Flip four ways, if they are true you should get uniform bluing on each of the pin contacts to the angle.

AlexO · Sep 16, 2017

dcsipo said:
Hi

i need to to make one of these....

12'x x 6' 1"+ depending what cast iron piece i get a hold of.

View attachment 208036

the front edge 45[SUP]o[/SUP] I will scrape it on all sides. The question comes in, how do i measure the 45[SUP]o[/SUP] on the front to make sure they are perfectly centered and truly 45[SUP]o[/SUP] and parallel to the back. I have a 3" wide 5" sine bar, i think i can balance it on it and set it at 45[SUP]o[/SUP], but i see too many potential errors creeping in. I have a pair of B&S V blocks i could qualify them first and use them but they only have a 2.5" sloping side. I would like to get the whole thing within 2 thenths overall. i know i can scrape to that, but not certain i can measure to that with my setups. Anybody have some oldtimer tricks up their sleeves?

dee
;-D

Sounds like a very tall order to me. I don't think you can scrape 12' within 2 tenth, that'd be 5um for people like me. How are you going to support it ? For the 45 deg edge you'll need to manufacture a reasonably long rail registering to the finished bottom edge and then gage against that. The only trick I know is to first define the 45 degree edge and then slowly sneak on the parallel flats without touching the edge again. Given the 3.5 meter length, I think the old codger who taught me scraping would've called it quits. You'll need to wave scrape it and you'll need pre-made patterns to hold 5 microns over that length. And temp controlled room. I wish you the best.

dcsipo · Sep 16, 2017

AlexO said:
Sounds like a very tall order to me. I don't think you can scrape 12' within 2 tenth, that'd be 5um for people like me. How are you going to support it ? For the 45 deg edge you'll need to manufacture a reasonably long rail registering to the finished bottom edge and then gage against that. The only trick I know is to first define the 45 degree edge and then slowly sneak on the parallel flats without touching the edge again. Given the 3.5 meter length, I think the old codger who taught me scraping would've called it quits. You'll need to wave scrape it and you'll need pre-made patterns to hold 5 microns over that length. And temp controlled room. I wish you the best.

..if it was all square and parallel then it would no big whoop. I am just going to machine the nose clamped in V blocks flip and repeat till i get a reasonable nose in the center. Once i have the flats established. then i will scrape the parallel sides and the short square sides, that can be done within the desired tolerance. I have a plate that is better than 1 tenth per foot. and i can measure square within 1 tent per 6". so i can scrape to that. With the sine plate and blocks i can set a precise 45[SUP]o[/SUP], but it is pretty small support surface, only 25% of the entire length....so drooping may be an issue. If i calibrate my v-blocks i can support the bar at the Airy points, so droop is less of an issue. I can put a gage block on the scraped 45[SUP]o[/SUP] and measure it from the surface plate flip repeat. The limit of my measurement tools is 1 tenth. so that i the reason i was hoping for 2 tenths...

obviously getting something like this stable is a challenge use many clamps and maybe a rod to hold it in the groove

dee
;-D

dcsipo · Sep 16, 2017

Milland said:
Not an oldtimer (yet), but something that comes to mind is a narrower second plate of the same thickness, with four precision pins bedded in the plate such that when they're flat on a plate they mate at tangency. Flip four ways, if they are true you should get uniform bluing on each of the pin contacts to the angle.View attachment 208037

how do you get the pins same height from each side? That would be a challenge for me

dee
;-D

Milland · Sep 16, 2017

dcsipo said:
how do you get the pins same height from each side? That would be a challenge for me

dee
;-D

That's a little more "conventional" machining, the plate can be set upright on a surface plate, with a tenths test indicator running over the tops of the pins. It does require a lot of inherent accuracy in making the pin plate, probably more than you want to deal with for a one-off. I'd consider machining two square grooves as a trough for the pins, then use jack screws or wedges to bring each of the four pins to height.

Once geometry is set, then epoxy the underside of the pins to fix them. If your 45 degree plate must have a sharp peak, then a further relief groove will have to go between the two pins to clear it.

Plan B is "and then a miracle occurred". That doesn't happen often in my shop...

Peter. · Sep 16, 2017

dcsipo said:
..if it was all square and parallel then it would no big whoop. I am just going to machine the nose clamped in V blocks flip and repeat till i get a reasonable nose in the center. Once i have the flats established. then i will scrape the parallel sides and the short square sides, that can be done within the desired tolerance. I have a plate that is better than 1 tenth per foot. and i can measure square within 1 tent per 6". so i can scrape to that. With the sine plate and blocks i can set a precise 45[SUP]o[/SUP], but it is pretty small support surface, only 25% of the entire length....so drooping may be an issue. If i calibrate my v-blocks i can support the bar at the Airy points, so droop is less of an issue. I can put a gage block on the scraped 45[SUP]o[/SUP] and measure it from the surface plate flip repeat. The limit of my measurement tools is 1 tenth. so that i the reason i was hoping for 2 tenths...

obviously getting something like this stable is a challenge use many clamps and maybe a rod to hold it in the groove

View attachment 208038

dee
;-D

Your milling machine has no facility to nod? Might be easier to nod it forward 45 degrees, take some trial cuts and adjust the nod or shim one edge of the plate to hit your 45.

AlexO · Sep 16, 2017

dcsipo said:
Hi

i need to to make one of these....

12'x x 6' 1"+ depending what cast iron piece i get a hold of.

View attachment 208036

the front edge 45[SUP]o[/SUP] I will scrape it on all sides. The question comes in, how do i measure the 45[SUP]o[/SUP] on the front to make sure they are perfectly centered and truly 45[SUP]o[/SUP] and parallel to the back. I have a 3" wide 5" sine bar, i think i can balance it on it and set it at 45[SUP]o[/SUP], but i see too many potential errors creeping in. I have a pair of B&S V blocks i could qualify them first and use them but they only have a 2.5" sloping side. I would like to get the whole thing within 2 thenths overall. i know i can scrape to that, but not certain i can measure to that with my setups. Anybody have some oldtimer tricks up their sleeves?

dee
;-D

If you can scrape 12 foot by 6 foot within 5 micrometers I'll say you are the best scraper hand in the known Universe.

Edgar10937 · Sep 16, 2017

Maybe I missed it but, how thick will this noodle (Rich's term) be?
Do you have a plate to blue it on?
Edgar

Sent from my SM-G935V using Tapatalk

lucky7 · Sep 16, 2017

Perhaps you mean 12 inches by 6 inches by 1 inch? I hope... Otherwise...

Lucky7

dcsipo · Sep 16, 2017

Peter. said:
Your milling machine has no facility to nod? Might be easier to nod it forward 45 degrees, take some trial cuts and adjust the nod or shim one edge of the plate to hit your 45.

My mill is banished from this site

. It can only tilt sideways. it is a Taiwanese knee mill, and it can only travel 6" in y. I could take it somewhere else to machine it. but because i will scrape it anyway, it just have to be within a few thou. I do not mind refining it using hand tools. I also thought about making some larger adjustable V blocks for the milling op. Not to concerned about getting it close enough for scraping

. I am more concerned about measuring it, it needs to be quite precise.

dee
;-D

AlexO · Sep 16, 2017

dcsipo said:
My mill is banished from this site . It can only tilt sideways. it is a Taiwanese knee mill, and it can only travel 6" in y. I could take it somewhere else to machine it. but because i will scrape it anyway, it just have to be within a few thou. I do not mind refining it using hand tools. I also thought about making some larger adjustable V blocks for the milling op. Not to concerned about getting it close enough for scraping . I am more concerned about measuring it, it needs to be quite precise.

dee
;-D

You should pay attention to what you're typing. It seems you meant inches not feet. There is a difference between ' and ". 12" by 6" by 1" is a non issue.

dcsipo · Sep 16, 2017

AlexO said:
You should pay attention to what you're typing. It seems you meant inches not feet. There is a difference between ' and ". 12" by 6" by 1" is a non issue.

oh...sorry the the piece is 12" long and 6" wide...

dee
;-D

TGTool · Sep 16, 2017

Since I haven't actually done this, my proposal would be only speculative.

It seems to me that you can get there with some fairly simple pieces but it's going to be a process of iteration. That is, checking angle, centrality, and parallelism separately and then working as necessary. A little like doing all the checks on a machine tool before you start scraping.

For the 45 degrees, you'd have to make a gauge to check but it could be only 3" or 4" long and an inch wide. Scrape the inside two surfaces to 135 degrees. The length should be enough that you can verify angle with a sine bar and the flatness with whatever other references work best. So you've got an angle master and can check from a flat side to the angle face with bluing to verify contact. You'll no doubt have other flatness references so if the face is flat along its length and checks as the correct angle each side is good up to that point.

Then you'll also need a parallel you can clamp to a flat side, set the workpiece up on the surface plate on its back edge, and put a roll in the gap with the angle face. Now you can make four measurements to see if the flats are parallel with the back edge and the same both sides. If not, you'll know which sides and ends to work on, using the angle master again to be sure you're not getting off in the weeds.

CarbideBob · Sep 17, 2017

First off that back better be 1 micron or less square and both flat big sides in that range or you need to establish a real datum.
Several ways to measure it but flipping the part means it has to be perfect or you need a way to know and comp it out.
Depends on what your front vee has to track to.
This is a tight number and in the range of a piece of not visible dust so a clean room would be advised by a sane person.
Yet it can be done in a normal shop with care.
Not sure what you are trying to hold to what. Think functional gauging when you run into this stuff, not just easy to measure.
Multi indicators may make sense with add and subtract built in or done manually.

You have two 90 degree lines on each surface.
Lengthwise sit it on a plate with a good dti against a block and slide it. Easy to get end to end on one line. Slide the part not the gage and ignore the first bounce as you load the system and you have to watch or memorize high as any scrapped surface bounces all over hell.
Now is that 45 nailed all the way down? Raise/lower the dti to get more lines but you might be straight lengthwise while at 44.5 degrees so that is another check.

Can this be stood up with a vee block on top and a indicator on top of it to get the vee tracking. Maybe a second to do sideways?
Tracked in a vee while checking what the back and sides show?
Not sure what you are making. 1000 ways to skin the cat, some are easier but helps to know your final destination.
Bob

J_R_Thiele · Sep 17, 2017

For the 45* make (lap) a cylinder 1.5000 in diameter, and another .6697 in diameter. when they are in contact with each other on a surface plate a line across the two will hit the plate at a 45* angle.
If the second cylinder is .6698 the angle becomes 44* 59 min and 31 seconds.

You can also generate 45* by scraping 3 pieces, but do not have time to post that now.

Paolo_MD · Sep 17, 2017

Dee,
I concur with several others: if you describe what this piece is for, it is much easier to give you better targeted suggestions.
My guess is that it has something to do with rebuilding your B&S 618 grinder. In that case, I'd have three comments: first, who is guaranteeing you that the angle of the V was is indeed exactly 90°? Probably, it would be much better to use a less worn portion of that way as your angle template (by scraping flat and parallel the two sides first, you can check the symmetry of your angle by reversing the piece in the way).
Second, Having the angle of the V ultra-precisely accurate doesn't really matter for the functioning of your grinder and you can deal with that by marking the correct orientation you need to use for your template and the V-block(s) that you need to make as well.
Third, segwayed into from the previous comment, in the rebuilding process you'll likely need at least one V-block matched to the mating way and, if you make that first, you can use it to test the parallelism of your 45° angle to the back, by having your piece resting on the back and measuring from the top of the inverted V-block.

Paolo

dcsipo · Sep 18, 2017

Paolo_MD said:
Dee,
I concur with several others: if you describe what this piece is for, it is much easier to give you better targeted suggestions.
My guess is that it has something to do with rebuilding your B&S 618 grinder. In that case, I'd have three comments: first, who is guaranteeing you that the angle of the V was is indeed exactly 90°? Probably, it would be much better to use a less worn portion of that way as your angle template (by scraping flat and parallel the two sides first, you can check the symmetry of your angle by reversing the piece in the way).
Second, Having the angle of the V ultra-precisely accurate doesn't really matter for the functioning of your grinder and you can deal with that by marking the correct orientation you need to use for your template and the V-block(s) that you need to make as well.
Third, segwayed into from the previous comment, in the rebuilding process you'll likely need at least one V-block matched to the mating way and, if you make that first, you can use it to test the parallelism of your 45° angle to the back, by having your piece resting on the back and measuring from the top of the inverted V-block.

Paolo

Nope, it is not for the grinder itself. As you said the V ways are just V ways, they just need to mesh into one and other and one is the master for the other. All i am trying to make is a knife edge square and i want the knife edge to be in the center. I think i can make one and it will be a fun project. The reason i am keeping it rectangular because that way it is self proving. Flipping it back and forth i can prove it to what i can measure with my dti. Still scratching my head about how to center the knife edge properly and keep the sides at a reasonably precise 45[SUP]o[/SUP] The most important thing i want to achieve is to keep the "knife edge" centered, the two sides even and the angle the same on both sides. If all of this is futile, i can make the square with an asymmetric knife edge, just move it to one side completely. The only downside is that i will have an edge with a lees than 90[SUP]o[/SUP] included angle and not a symmetrical 90[SUP]o[/SUP]. I was going through sketches how i can measure this and all seemed too farfetched, and unstable.

dee
;-D

Alex McGilton · Sep 20, 2017

If it's a knife edge square your after then why not buy a no name brand knife edge square then make a lapping project of it by bringing it into square. I can appreciate the challenge you wish to peruse in forming the geometry , however would the attributes of the two 45deg flanks be useful enough to justify their creation over a simple rectangular prism .

An alternative that comes to mind for the original design is to make tall thin V-block then insert a piece of ground square stock, The V can be checked by using a round pins and V-blocks as mentioned above, then secure the square bar by counter sunk screws.

Paolo_MD · Sep 21, 2017

I've always thought about knife-edge instruments as hardened, ground, and lapped. Scraping the knife edge, I think, defeats the purposes, since you'll end up with a ragged edge. Somehow like using a saw blade instead of the edge of a ruler to check if something is flat.

Paolo

this is more metrology then reconditioning, but i need to make a tool for alignment

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