Scraping a 54" Straight Edge
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- เผยแพร่เมื่อ 13 พ.ย. 2018
- Taking a rusted up old Cast Iron Straight Edge and re-scraping by hand the working face using a 36" SE as master.
I run into a number of challenges along the way, which I try to explain to help anyone looking to undertake a similar task.
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Awesome video! I love visual aids! All these scraping videos is keeping this knowledge alive.
Thanks for watching and commenting. All the best Mat
Your videos are such great documentation of the process. I’ve found them very helpful in working towards improving my milling machine. 👍
Hi Ben, why thanks for the positives. I try to show the thought process as I go along - Im no machinest or time served 'fitter' , So cant reallyshow a load of fancy skills or super efficient machine work - there are plenty of channels which do that far better than I could hope. So I show how and why I do it in a certain way. Im glad it helps. Feel free to share the video - be nice to pick up a few more subscribers. All the ebst with your mill. Mat
A painstaking process, well done.
there were times when I wished I was fishing !.... the end is in sight - couple of six footers to go and then Im onto the lathe bed.
Enjoyed, looking good!
ATB, Robin
Been watching your Holbrook rebuild.extreemly interesting especially as I had one for last 30 odd years in my home shop.as jam getting ever closer to retirement age I wanted to get rid of it while I was still able but couldn't find any body interested or able to shift it. Ended giving it to a mate of mine and ended making clutch housing bearings for him .can't Waite for end results grate work thanks for sharing
Looking really good there, don't sell yourself short .... :)
Fair play Matt.
It would take a lot more than a cup of tea at the end of the rainbow to keep my motivation up to a point where I was actually productive.
Keep it up mate.
It will be worth it in the end. 😎
Think I may invest in a nice malt bottle as a prize for completing the last SE - I may even win the comp' unless I cheat of course :-)
Thanks for use Empiric mate! Hate the sterile continental metric.
I have to use both, but am more familiar with thousandths of an inch than hundredths of a mm. Yet when I get past 6ft, I go to meters ! Bloody stupid UK education system converted when I was in primary school - they chose CM's which is next to useless as a direct referance. MM's or Meters would have worked but CM's - rarely used on drawings or tables. Mind, those fractions of an inch still make me scratch my head !
pretty cool, just what I needed to start getting some ideas for my straight edge. I was wondering if you could scrape a dovetail, lets say a 12" long dovetail with a shorter straight edge or is it better to just start with a longer one?
if you have the chance at a longer SE go that way - it makes the entire task more straightforward. So if you are trying to scrape 18" try and use a 18 - 20 " SE or surface plate. Step scraping as you can see is possible but it adds another risk of error. My advice get a SE or surface plate long enough to do the task. In my case, I didnt have a 6ft SE and am working up older castings from my 24" granite to get to 6ft. tedious to say the least. :-)
oh, ok, just as I suspected. Thanks for confirming that.
Thanks for taking the time to do the intro explanation bit. It helps to see the process you used to finish off that straight edge. I just bought a five footer myself, it has a little rust damage but not the deep rust pits you dealt with. It is dam it's heavy. Will you use an overhead support to reduce the weight of the 54 when working on the six footer? I think the 54 will prove challenging to print with. Anyways, congrats great job.
Hi Mark, I can tell you it was a lot less effort with paper aids than lumping the SE around to re-shoot the sequences lost ! Ive been thinking about the 54" as master - lifting it up and on to the 70" . The main issue is being able to invert the 54" between printing, re-inking / spreading and it sitting on its feet while I scrape - Ive no solution at this stage. I took the first prints yesterday manually and it is 'do-able' all be it not too frequently. I have to shuffle a few things about to reduce the distance it has to be carried and remove the current 90 degree rotation. basic logistical stuff to minimize the effort. If I run out of puff, I will have to rig up a pulley and counter weight from the roof joists - its just more stuff to get in the way and drop dust etc etc. Ive seen some complicated counted contraptions which reduce the effort but all are in far larger work places so have room. If you can - then do it !
Seeing your shop really drives home how much space I have. I'm amazed at what you have packed in there.
Inverting it will be a challenge. You need something you can lower it on, clamp it to and spin. Kind of a scaled down car rotisserie. I think on practicalmachinest forest addy said he used track for a garage door screwed the the ceiling and some long door springs to reduce weight. but I think he used the track to go from project to granite plate. Could you reink with the straight edge in the air? It will be interesting to see what you come up with.
Managed to lift , invert and print yesterday by hand. As the 6ft SE is such a large surface, the printing cycle is quite infrequent. So with luck I may get away without adding any further complications.
what are you going to do the filling with zinc has the same melting point as lead
I left the 'pits' on the SE I concluded that if the SE is 'rubbed' a distance greater than the size of the pit is makes no difference. In reality a 2" shuffle of the SE in use is pretty small. I do have to be sure the pits are clean before use and dirt could lodge in.
For such deep pitting, would it be feasible to fill in with brazing?
yes, that was the approach used by Robin Renzetti on Tom Liptons little level. Robin used a TIG torch and silver solder (low temp) to minimize potential distortion from the heat. In his case it was a casting inclusion not rust pocket. It may be something I go back to address in the future when I have funds to buy the Argon bottle & Gas for my Tig Welder. At this stage I dont see that the pits of despair will be too much of an issue in use.
Look on the bright side, in those areas it increases your PPI! (Pits Per Inch.... )
One was so big it has been named and there are a team of cavers exploring the inner reaches....
@@somebodyelse6673
Did you make that scraper?
I use a number of scrapers - most I have made, some use a Sandvic carbide tip, others are just carbide Ive found.
Can i ask is there radius whem rough scraping also can i scrape cover like 100% if its scrape alignment
Rough scraping is all about getting the material off evenly without digging holes as fast as you can (minimum effort). If you use a small radius, you can take a deeper cut but its narrow so you need more of them and you run the risk of making some much deeper than others - this then means you have to scrape the rest of the area down to that depth before moving on to going for contact. In my view, its better to take a broader scraper (large radius) and overlap your scrapes by 50% side to side and 30% end to end, that way you move a lot of material without digging holes. Which makes the next step easier. Scraping for alignment is generaly rough scraping (as above), then as you develop the surface you keep measuring the alignment to ensure it remains within tolerance. You can see this on the video where I re-scrape the Holbrook lathe bed.
Thanks fo rwatching. Mat
@@lookcreations should i use a non radius blade with corners knocked off or it has to be with radius .really appreciate your help theres no convenient way to do research on scraping and im still kinda unsure with dots per inch i know 40dpi is what precise machine tool have
Can i use scraping for dimension fit also what happens if you do not criss cross the scrapes? Sorry for the questions(i shall repay you by handing down this knowledge to anyone interested and want to scrape xd .)
It is very hard to scrape with a flat blade. A large radius say >90 mm . If I hold my blade against a straight face, the 30 mm wide blade might be 0.5 mm down at each side for roughing.
As a guide.
15 points per square inch with >50% contact for slow moving faces, 20-30 ppi @ 50-75% contact for more accurate bearing or faster moving. 30+ ppi looks good but doesn’t gain you much over 25 ppi at 50% contact. Static faces might by 5-10 ppi at 80%+ contact.
you dont bother to drill and solder those bad pittings of rust corosion sink holes? ? ... then fill them up with led ? or other ? ... and flatten them again?
if I was looking to create a 'master' but on this SE I didnt bother. If the area had been larger I might have split it and repaired part of it to reduce the size.