Scraping Blue?

Jewellers rouge is an abrasive and I doubt whether you could get Red Lead today. At one time any paint manufacturer sold it

Roy

I use "bearing blue" purchased from my local car parts store.

Most important thing is not the specific brand etc etc but to remember the golden rule of not to put too much on the job. Wipe it on with one finger, then wipe it off with another. What's left is about the right amount.

Having a light source behind the job, whether a window or a lamp, and getting the right angle of sight and light is important too.

Andrew,

You use the yellow high lighter by putting it on the part you are scraping. Wipe on a very thin coat. It should be dry to the touch. I.e. not transfer over much if you touch it. I use an old cotton rag to wipe off any excess. In fact most of the time there is enough yellow on the cotton rag that I use that to apply it and wipe off excess. Plus I use my hand to wipe over to make sure it is nice and evenly applied. Your hand is very sensitive to feel for any contamination as well. So I always rub my hand over the yellow or blue. That is another reason why it is nice to have a water based ink. Having said that I seem to have some blue stain on my hands most days.

Then when you present the part to your plate and blue it up, the blue is much easier to see. I use this when the blue is starting to get to very small dots (i.e. when going from 30 PPI and getting close to ~40 or greater PPI). I also use it if I have a high spot problem that I can't easily see.. I.e. I put the yellow on the part. Then I present it to a clean granite plate and "polish" the part. The high spots are polished such that all the yellow ink is rubbed off the high spots. This makes it very easy to see the offending spots. Again when you are getting close to finished on a high PPI job a couple of rogue high spots can make it look like your going backwards. It makes all the difference to spot them easily and this way you can identify them and bump scrape them off, and then re-print the part.

Of course it is enough to do that with no ink as the high spots get polished by the granite anyhow. All the yellow does is simply make it easier to see what you are looking for.

I have found that everyone I've met or discussed the use of the water based inks with, that have tried it, prefer it to the the stuart's. Of course it is not essential, it just makes the job easier and also easier to clean up afterwards. DAPRA amongst others sell it in retail in the USA. Recently I have been told that the BIAX dealers around Europe are starting to sell it. I've not asked **LINK** who are the UK BIAX dealers.

Regards,

Steve

Again it would be great if an enteprising company in the UK started to sell.

Russ, thanks for the clarification on the cement tint. I had visions of some horrible grit!! Obviously I've never used the stuff...

Pete

Still have a tin of Stuarts marking blue from many, many, moons ago... did some practice back in Jan. to see if I still have the knack... blue dabbed lightly on plate glass, with a balled up piece of cloth so the layer was translucent...



I reckon I have...

George.

Edited By mechman48 on 16/05/2017 15:04:55

Hi,

I am not good at photography and don't often take pictures but please see the photo below which is the best I have to show the benefits of high lighter and blue in use together.

This is a zoomed in section of a 36" dovetailed straight edge that I have scraped in from a casting, from memory it is about 1.5" wide. For scale there are about 40 PPI on average some times less and some areas more. I have also got a few scrapes where I slipped and I spoiled the finish and also more seriously I "rolled" the edges of the straight edge. This was not planned and is undesirable. You can see that there is no blue contact on the edges. This means spotting tight in to an edge  is impossible. I unfortunately need to redo the work from scratch as the rolling is about 1 thou low compared to the blue high spots.

However what I hope you can see clearly is how easy it is to spot the high spots with the yellow high lighter. The print is clear and does not look like a smudge.

Steve

Edit: for typos

Edited By SteveI on 16/05/2017 15:37:48

Steve,

A very impressive photograph! I have never seen such contrast on a rubbed surface. I didn't get my wires twisted and do appreciate that it is the US water based system we are talking of. I got my fingers twisted instead and didn't type what I intended!

I am one of those unfortunate people that get engineering blue just EVERYWHERE, except for what I am trying to coat! I assume the water based products are not nearly so messy?

I never expected this thread to reveal such a wealth of detail about scraping and systems used for highlighting high spots. It has been a real education and there may be more to come. I shall mull over all the helpful advice and see where to go. It is hardly expensive to try most suggestions (including the water based system). I can then see which one suits my needs best.

Thanks for such a response!

Andrew.

Yes, jewellers rouge is an abrasive. I remember now! It was used to finally lap in the diesel injector pistons on large diesel engines. We were warned NEVER to stop moving the piston. I did once and the piston welded itself in, ruining the entire block of 6!

The foreman was not pleased and let me know in no uncertain terms; it never happened again!

Brian

Andrew,

My photo is using the 2 colours of the volkcorp canode i linked to previously. I have limited personal experience and am a hobby scraper, but like I have said people that have tried the water based products seem to prefer them to the stuart's, no massive sample set though... Note that many people do wonderful work getting on just fine with the stuart's. I personally found switching to the water based helped me get better at efficient use of time when scraping.

In that photo the yellow was rubbed on via a cotton rag (old t-shirt) and the excess rubbed off with the side of my hand. The hand also smooths out the variation in thickness. The blue was rolled on to a granite plate and the excess wiped off. At this stage in the job I had very very little blue on the plate. Note also that as an experiment/learning process I tried to scrape that straight edge very deeply the variation between the high and low spots is ~0.0006". Much deeper than I would a machine bearing. The idea was to create a straight edge that was more robust to wear. I wanted the tool to last longer before it needed a rescrape. The experiment was only partially successful, I got the depth I was looking for but with pushing harder I lost control and had a few slips when bump scraping and consistently rolled the edges.

I have since learned that rolling the edges is a problem on a machine bearing because it creates an unnecessary gap for swarf/dirt etc to get in to the ways and leads to excessive wear. So it is a very bad habit to get in to.

Also to correct an error in my post this picture is not from the dovetail straight edge. (Not that it matters much but the dovetail straight edges is about 3" wide on its flat bottom.)

Steve

I have water based Canode in red, blue and yellow and Stuarts oil based compound in blue and red.

I find that the Canode product is significantly more coarse than the stuarts product and does not transfer as well with a thin layer. It also needs re-wetting when left for a while or it won't transfer at all well.

Having said that, I get very good results by applying the yellow Canode as a background and thinning it using glass cleaner (detergent type, not Windolene!), then using the Stuart's blue for spotting.

Canode will give good marking if you are scraping half a thou, but not if you are scraping half a tenth.

Mark,

Very interesting points about canode vs stuarts. You are correct it does dry out. I also use window glass cleaner to thin the yellow as needed and for general clean up.

I will do some experiments with using the stuarts for finer work. Thanks for the advise.

Where did you source the canode?

Steve

I had to order it direct from Volk Corporation in the States. They were quite helpful with shipping to far foreign lands, even though it was unsusual for them. I couldn't find any UK or European resellers, although they could well exist.

Hi gents,

My first post here and I know this thread is a few months old but some members will recognise me from other forums so I thought I'd just chime in. You can buy canode in the UK now you can get it from aetools in Bolton. It's not advertised on their site yet but they are the UK importer so if you need some give them a call or send an email. I have no association with them I only mention this because I'm placing an order myself and this thread came up in a search. I thought it would be handy for the scrapers here to know that you can get it locally now.

Cheers.

Pete

Regarding Stuarts Micrometer blue.

Are you diluting it with some oil or use it as it is?

I have found diluting useful but I am still new to scraping, so I wonder if it is legitimate approach?

Martin

I do dilute it with a light oil. Often you'll find when you open a tube that some oil has separated out. I put down a small bead of blue ready for rolling out and apply one single drop of oil, it's a bushing oil similar to 3-in-1 oil. I find that this makes it less likely to suck the part to the plate and it does print much better. I have a small 6" plate which I roll out the blue on to load the roller then roll it out on the plate I'm using for spotting.

Pete.

Edited By Pete Rimmer on 09/11/2017 20:36:27

The brands I am familiar with are Dykem Hi-Spot Blue and Canode. Dykem was often put on the underside of machine handles as a prank.

I have used Prussian Blue oil paint, works very well in my opinion. The finger does seem to be most effective for application but it is very messy.

Mike

Yeah, that's what you tell us now .

I've enjoyed following this thread.

I think the lack of availability of scraping tools and consumables is perhaps a contributing factor to the decline of the skill??

Could someone give Ketan a nudge at Arc, it would be good to get some red/blue Volkcorp Canode in stock, and perhaps a small section dedicated to hand scraping bits and pieces!

They aren't so plentiful, I've had to make most of what I have.

Scraping is now almost relegated to home enthusiasts and whatever handful of rebuilders of old equipment there are still going. Not much of a market for the equipment you'd need but it wouldn't take much for someone to at least stock a couple of boxes of the small bottles of spotting dye.

The most difficult stuff I've had to find is the cast iron straight edges. Very thin on the ground nowadays and a lot of what you see isn't fit for use until it's been scraped in itself.

Pete.