daedalusminos
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Good work, that's alot of hand scraping! Interestingly your step scraping technique is subtly different from mine, in that case I would have scraped 9, 9&8, 9&8&7 etc.
- Thread starter Pete.
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Pete.
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2 routes to the same destination. I guess your way you always know what you've done and what you have left.
Pete.
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Well, I now have the ways parallel to 0.0002" over 16". I think that's good enough, the scrapes are nearly that deep. I also got the ways very flat to each other. To test it I blued up the console flat ways (which are already scraped flat) and put a few drops of light oil on the ways then ran the console table up and down a few times. The tripe down the middl is because of the oiling groove in the console.
Pete.
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Right so here's why it doesn't really matter too much if the two main ways are 'level' with each other so long as they are parallel.
I have previously scraped the mating face on the console table flat right across with a surface plate. It's got good bearing and a nice spread of blue dots which is what I wanted to do this evaluation. When I was scraping I could see that the oiling groove closest here was shallower than the furthest one which would indicate that the way is 'lower' than the far one.
I've put the console on my biggest surface plate with the scraped face downwards and taken some readings with a digital gauge with half-tenth resolution. Let's suppose that the machine is new and the main ways are perfectly flat and true to each other in every respect which they should be when it's new. If you put the slide onto a flat plate then all of the upwards faces should indicate completely parallel to the bottom face that's against the plate. Not surprisingly, they aren't.
I had to use my large Mercer comparator stand to get the long reach across to the far way and I still had to be careful to take good readings as the smallest touch on the post would change the reading. I moved it about only by pushing on the base and I kep going back to othe zero point to check it hadn't moved.
So the readings tell me that the (underside) way on the right is lower by about 1.5 thou than the one on the left (the readings on the top and bottom edge are from the ways here not the planed face).
What I don't know is whether the RH ways have worn a thou and a half since this machine was new or last rebuilt, or whether someone has deliberately scraped one side down to turn x-axis into perpendicular alignment with the y-axis dovetail. I can easily scrape this down so it's all parallel again but if I do that and then later find that it I have turned the x-axis back away from where it should be its a LOT more work to fix it by scraping that y-axis bevel way plus I'll then have a tapered gib that's sunk in past it's limit of adjustment.
So there's no need to worry whether the long ways are a couple of tenths out level when you check the mating ways and find them out by 10x more. All that matters is when you're finished they bear against each other properly and the table is in alignment.
I have previously scraped the mating face on the console table flat right across with a surface plate. It's got good bearing and a nice spread of blue dots which is what I wanted to do this evaluation. When I was scraping I could see that the oiling groove closest here was shallower than the furthest one which would indicate that the way is 'lower' than the far one.
I've put the console on my biggest surface plate with the scraped face downwards and taken some readings with a digital gauge with half-tenth resolution. Let's suppose that the machine is new and the main ways are perfectly flat and true to each other in every respect which they should be when it's new. If you put the slide onto a flat plate then all of the upwards faces should indicate completely parallel to the bottom face that's against the plate. Not surprisingly, they aren't.
I had to use my large Mercer comparator stand to get the long reach across to the far way and I still had to be careful to take good readings as the smallest touch on the post would change the reading. I moved it about only by pushing on the base and I kep going back to othe zero point to check it hadn't moved.
So the readings tell me that the (underside) way on the right is lower by about 1.5 thou than the one on the left (the readings on the top and bottom edge are from the ways here not the planed face).
What I don't know is whether the RH ways have worn a thou and a half since this machine was new or last rebuilt, or whether someone has deliberately scraped one side down to turn x-axis into perpendicular alignment with the y-axis dovetail. I can easily scrape this down so it's all parallel again but if I do that and then later find that it I have turned the x-axis back away from where it should be its a LOT more work to fix it by scraping that y-axis bevel way plus I'll then have a tapered gib that's sunk in past it's limit of adjustment.
So there's no need to worry whether the long ways are a couple of tenths out level when you check the mating ways and find them out by 10x more. All that matters is when you're finished they bear against each other properly and the table is in alignment.
pressbrake1
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Fixed head are more or a pita but if there’s a swivel head or a sliding head then not too bad
Used to do a lot of on site Huron’s back in the 90’s as the ram head would suffer
Three point the column dead level then scrape in to level to start the clock to column or bed and pitch if necessary
Fixed head machines have to be scraped to spindle
Good work Pete btw
pressbrake1
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Just to clarify
YouTube speak via the king
He and those who have learned via t net
Step scraping in U.K. is called pitching or blocking
YouTube speak via the king
He and those who have learned via t net
Step scraping in U.K. is called pitching or blocking
Pete.
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I never heard it called blocking but then you only know what you've been taught. Pitching is a nice term, makes sense 'pitching the way'.
I haven't tried to 3-point the column and using a level because my workshop floor is too thin. We're on chalk here so no need for a mega thick slab but if I walk around from one side of the part to the other you can see the bend in the floor by watching the bubble move.
I haven't tried to 3-point the column and using a level because my workshop floor is too thin. We're on chalk here so no need for a mega thick slab but if I walk around from one side of the part to the other you can see the bend in the floor by watching the bubble move.
roofman
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cant see it any better than that out the factoryA final round of scraping and I have got this to a condition I don't think I can improve on. I set it up like this:
View attachment 340498
And it came out like this (excuse the loud music it's my favourite radio show):
Dropbox
www.dropbox.com
Pete.
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Next I had to check the height of the front flat ways against each other. 2 posts up I had mapped out the console and found one way higher than the other and I didn't know if it was wear or deliberate or a combination of the two. I had a think about how to check it and figured that if I could get a square on the z-ways and an indicator to follow the y-ways dovetail I could at least see if the are square to each other.
FirstI had to make sure the dovetail way was actually flat or the readings would be meaningless. It wasn't
So a good amount of hand-scraping later...
...I got it at least good enough to take meaningful measurements. I stood my square up on gauge blocks to span the raised centre section. If I run an indicator up the side whilst the stand is following the dovetail way it should read zero all the way up if those ways are level.
I got a stop with the comparator that locates in the slot and clamps with a screw. I put that on the underside spaced out with washers so the edge of the 3" wide stop could touch the dovetail. It's not ideal but it's good enough for a basic check. I'm holding it here with my knee so I could take a photo.
I zeroed the gauge at the bottom and ran it up to the top of the ways - 4.5" travel.
As you can see, the ways are not level, or more properly not perpendicular to the y-axis travel. The numbers don't exactly match the figures I got from measuring the console (2.5 thou over 4.5" compared to 2.5 thou over about 7") but they are in the same direction and my method of measuring here is far from ideal, I got thin edge contact on the ways and a loooong extension holding the indicator.
Where this leaves me now is I must scrape in the top slide and fit it to the y-axis ways. If I do this, I can put an indicator on it and use the actual slide to hold the indicator. Then I'll have a nice solid mount for checking the console ways. There's no point repeating the check abouve I already know they are several thou out of level and that the console has already been scraped accordingly. I will use the slide to check against the x-axis flat ways and get THEM square instead.
FirstI had to make sure the dovetail way was actually flat or the readings would be meaningless. It wasn't
So a good amount of hand-scraping later...
...I got it at least good enough to take meaningful measurements. I stood my square up on gauge blocks to span the raised centre section. If I run an indicator up the side whilst the stand is following the dovetail way it should read zero all the way up if those ways are level.
I got a stop with the comparator that locates in the slot and clamps with a screw. I put that on the underside spaced out with washers so the edge of the 3" wide stop could touch the dovetail. It's not ideal but it's good enough for a basic check. I'm holding it here with my knee so I could take a photo.
I zeroed the gauge at the bottom and ran it up to the top of the ways - 4.5" travel.
As you can see, the ways are not level, or more properly not perpendicular to the y-axis travel. The numbers don't exactly match the figures I got from measuring the console (2.5 thou over 4.5" compared to 2.5 thou over about 7") but they are in the same direction and my method of measuring here is far from ideal, I got thin edge contact on the ways and a loooong extension holding the indicator.
Where this leaves me now is I must scrape in the top slide and fit it to the y-axis ways. If I do this, I can put an indicator on it and use the actual slide to hold the indicator. Then I'll have a nice solid mount for checking the console ways. There's no point repeating the check abouve I already know they are several thou out of level and that the console has already been scraped accordingly. I will use the slide to check against the x-axis flat ways and get THEM square instead.
Pete.
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Here's most of what I use. Narrow scraper, cranked scraper, wide scraper, Biax with several blades and my small scraper fitted with a bevel scraping blade.can you show a pic of your scrapers, be very interested to see them
On the left is spotting blue, angled stone and my trusty ink roller.
Pete.
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I use it more and more nowadays. If there's a huge amount to shift it's a bonus and I use it almost exclusively for finishing. I do a lot of hand scraping though especially on harder iron. Angled ways I always hand scrape unless I can get a real comfortable position then I'll perhaps use it.
Getting started on the y-axis slide ways. Here's the initial blue - not much contact and a wear ridge down the middle near the oiling hole. That's where the most wear is.
I scraped off the wear ridge down the middle and along the outside edge with my hand scraper. this part is very soft iron and easy to scrape a lot of metal off. Then I did a quick print and scraped the higher spots. You can see the most of the wear in the middle and little at the ends. This is because this moving way is longer than the fixed way otherwise it would be the other way around.
Then I got the Biax fired up and started shifting some metal.
These are very heavy roughing passes with a longer stroke. I'm not bothered about a pattern or keeping the scrape depths fairly even I just want to shift some metal.
And that's where I'm at. I will get this side roughed-in tomorrow and probably the second side too. Then I'll take some measurements.
Pete.
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So I rough-scraped in the other side in order to take some measurements. I have already previously rough scraped the top face too just to stop me gouging a plate if I put the top slide down on it. I stuck the slide on my biggest plate and took some readings.
From the readings you can see that 1. the right side is half a thou higher than the left and 2. the front is showing about 2.5 thou higher than the back (the front is the far end in this pic). It's actually probably not quite that much because there's a large overhang on the back end with it inverted which will affect the readings.
I need to scrape either the flat bottom ways or the top ways to make the top and bottom faces parallel, but which to scrape, top or bottom? That depends on the dovetail ways. If they measure the same width at either end I don't want to correct this measurement above because that will cause the dovetails to become narrower at the front (which needs scraping down more) than at the back, which will then need correcting by scraping the vee way. If the dovetail is wider at the front (unlikely) then I DO want to scrape the bottom face to correct parallel because that will also serve to bring the dovetails in closer to parallel.
I got some pins and gaug blocks to take some (admittedly very rough) measurements.
So the dovetail ways are narrower in the middle but the same at either end. I scrape the top. I will repeat this check several times as I do my next work.
Next I blued up the top ways on the main casting (which are already scraped flat with a surface plate) and set the top slide on them. I want to repeat the out-of-parallel checks by putting the slide on the ways it will work, and check the contact between the finished y-axis ways and the roughed-in top slide ways.
Here's the readings from both sides of the top flats. They both start at zero but that doesn't mean the faces are the sme heigh, just that I zeroed it each time.
Both sides showing 1.5 thou rise towards the front, less than the figure I got from the surface plate but this reading is more reliable so it's the one I'm going with. Now for the contact.
I could only check the contact towards the front because without the gib installed it would topple forwards when travelled too far. On the right I have great contact for a fresh-scraped pair of ways but on the left it's only contacting on the inside edge. To finish these flat ways I need to 1. Scrape the right hand side straight down half a thou and 2. turn the left hand way to bring the contact in right across. Once I do that I will only have the dovetail ways to scrape. I won't be scraping the top flats to correct the out of parallel until after the machine is built back up. I don't see any reason for it to be high at the front so much unless someone has done it deliberately so I'll get all the moving way geometry done first then do some checks on stuff like the hoizontal arbor and the milling heads before I touch it.
From the readings you can see that 1. the right side is half a thou higher than the left and 2. the front is showing about 2.5 thou higher than the back (the front is the far end in this pic). It's actually probably not quite that much because there's a large overhang on the back end with it inverted which will affect the readings.
I need to scrape either the flat bottom ways or the top ways to make the top and bottom faces parallel, but which to scrape, top or bottom? That depends on the dovetail ways. If they measure the same width at either end I don't want to correct this measurement above because that will cause the dovetails to become narrower at the front (which needs scraping down more) than at the back, which will then need correcting by scraping the vee way. If the dovetail is wider at the front (unlikely) then I DO want to scrape the bottom face to correct parallel because that will also serve to bring the dovetails in closer to parallel.
I got some pins and gaug blocks to take some (admittedly very rough) measurements.
So the dovetail ways are narrower in the middle but the same at either end. I scrape the top. I will repeat this check several times as I do my next work.
Next I blued up the top ways on the main casting (which are already scraped flat with a surface plate) and set the top slide on them. I want to repeat the out-of-parallel checks by putting the slide on the ways it will work, and check the contact between the finished y-axis ways and the roughed-in top slide ways.
Here's the readings from both sides of the top flats. They both start at zero but that doesn't mean the faces are the sme heigh, just that I zeroed it each time.
Both sides showing 1.5 thou rise towards the front, less than the figure I got from the surface plate but this reading is more reliable so it's the one I'm going with. Now for the contact.
I could only check the contact towards the front because without the gib installed it would topple forwards when travelled too far. On the right I have great contact for a fresh-scraped pair of ways but on the left it's only contacting on the inside edge. To finish these flat ways I need to 1. Scrape the right hand side straight down half a thou and 2. turn the left hand way to bring the contact in right across. Once I do that I will only have the dovetail ways to scrape. I won't be scraping the top flats to correct the out of parallel until after the machine is built back up. I don't see any reason for it to be high at the front so much unless someone has done it deliberately so I'll get all the moving way geometry done first then do some checks on stuff like the hoizontal arbor and the milling heads before I touch it.
Pete.
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Working on the Y axis slide dovetails today. I scraped both sides roughly straight good enough to do some checking. I wanted to check the dovetail was at the same angle as the fixed way on the left side (the non-gib side). To do this I blued up my straight edge with a thick layer of blue and used the straight edge to wipe it onto the angled way.
Then I oiled the top flats and set the slide in place, just slid it up and down a couple of times to transfer the blue.
Pretty good but it's tranferring mostly on the top half of the way and missing out a lot of the bottom. I scraped it a couple of rounds and tried again.
This is much better and even though there's now a strip along the top that is no problem because it doesn't contact there anyway. I had to scrape down a wear ridge and went a bit further so that I could make sure it didn't interfere with the straight edge.
Now I want to check if the dovetails are parallel. To do this I set up a dial indicator on a mag base. I couldn't get good readings at first until I put a second mag base just resting on the arm to steady it.
Had to read the dial from underneath. This is with the slide in the back position.
And this is in the front position. Half a thou difference.
The dial gauge says the ways need scraping more at the rear but not much. I am going to leave it for now until I get the tapered gib sorted. The reason is I don't think that this dovetail is tapered as much as the readings suggest. If I scrape it in now I might have to scrape it back later and if I do that after sorting the gib I'm going to be annoyed because there's less than 10 thou of adjustment range on the gib adhuster (1:100 taper moves about 100 thou to adjust only 1 thou so you run out of adjustment really quickly when scraping slides with tapered gibs. The gib is badly scored as it is so it's going to require a bit of work.
Then I oiled the top flats and set the slide in place, just slid it up and down a couple of times to transfer the blue.
Pretty good but it's tranferring mostly on the top half of the way and missing out a lot of the bottom. I scraped it a couple of rounds and tried again.
This is much better and even though there's now a strip along the top that is no problem because it doesn't contact there anyway. I had to scrape down a wear ridge and went a bit further so that I could make sure it didn't interfere with the straight edge.
Now I want to check if the dovetails are parallel. To do this I set up a dial indicator on a mag base. I couldn't get good readings at first until I put a second mag base just resting on the arm to steady it.
Had to read the dial from underneath. This is with the slide in the back position.
And this is in the front position. Half a thou difference.
The dial gauge says the ways need scraping more at the rear but not much. I am going to leave it for now until I get the tapered gib sorted. The reason is I don't think that this dovetail is tapered as much as the readings suggest. If I scrape it in now I might have to scrape it back later and if I do that after sorting the gib I'm going to be annoyed because there's less than 10 thou of adjustment range on the gib adhuster (1:100 taper moves about 100 thou to adjust only 1 thou so you run out of adjustment really quickly when scraping slides with tapered gibs. The gib is badly scored as it is so it's going to require a bit of work.
Pete.
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I made a gauge to measure how parallel the angled ways are. This gauge does depend on the flat ways being parallel and straight so they must be scraped first (which you would anyway).
Reading at the front:
And at the rear:
The rear is half a thou wider than the front which is much less than the half a thou over 6" I was getting in my checks yesterday. I don't know why that is but this reading feels more right. I don't know if I will scrape out that half thou or not. When the slide is fully forward with one of the working heads on it will have a lot of overhanging weight on it. That means the rear ways will be loaded so being that tiny bit tighter might help prevent it dropping when it's on full travel.
Reading at the front:
And at the rear:
The rear is half a thou wider than the front which is much less than the half a thou over 6" I was getting in my checks yesterday. I don't know why that is but this reading feels more right. I don't know if I will scrape out that half thou or not. When the slide is fully forward with one of the working heads on it will have a lot of overhanging weight on it. That means the rear ways will be loaded so being that tiny bit tighter might help prevent it dropping when it's on full travel.
