Camelback Straight Edge Scraping

[Richard King 2]

Tuning fork.....as in ringing a bell vs wringing a gage block. I usually lay the SE on it's side on a pipe and find the balance point and drill a 1/4 20 hole and tap it. If you don't have a lot of storage space you can set them on felt or styrofoam at 30% out to 25% on each side of scraped surface. I just checked and I see Challenge is still in business. I see they have the wood pads on the back, so you can flip it over and set it on those pads and braced so it doesn't tip over. http://challengeprecision.com/products/straightedges.html or email them and ask them.

 

[Richard King 2]

Here is the You Tube showing how Jan S. Rung 2 on the King-Way Brand Straight-Edge and scraping them. The show was filmed by Stefan G in the Denmark class he attended the ringing takes place at the 6 minute mark. You can also see how Jan cleans the dirt off the surface plate with his hands so he can feel the dirt on the granite. You can also see me wiping the Straight Edge with my hand before he sets it on the plate. Also see how he "hinges" the SE to see where it is high. Plus when he flips it over you can see the blue on the ends to support the hinge. Isn't You Tube amazing!

 

[wcunning]

...find the balance point and drill a 1/4 20 hole and tap it...

I don't quite follow that -- balance point in which plane/dimension? Is 1/4-20 really strong enough for a 6ft camelback (175~200 lbs, based on how much it sucks to pick up). If it is, then my concerns about having enough meat to drill and tap are largely alleviated.

I have been keeping mine in cases with Bessel point pads, here they're set out for the picture. I don't have space for those cases long term, nor do I have one for the 6ft'r yet, since that case would be *huge*. I think that hanging is a better long term solution, so once I have a game plan, I'll probably do that.

Thanks,
Will

 

[Richard King 2]

It's as easy for you to look up eye bolt specs as it is for me.
http://www.rigging.net/Eye Bolts.htm
1/4" is 400 pounds, 5/16" is 800 lbs, 3/8 is 1400 lbs. You can decide on which one is safe for you.
I am trying to educate everyone. You do what you have to do. The others reading from the world wide net can do it there way. I just know I have had 50 years of success doing it my way and over 30,000 students have never told me my methods don't work.

 

[ThunderDog]

So, all of this good information has got me thinking. I have a straight edge that has a large eyebolt at one end. I keep it hanging while in storage. I also have a 4' camelback but it is stored on the bessel pads. If a proper point were located to hang the camelback by one end would that be a better way to store it? Just curious.

 

[Richard King 2]

About 10 years ago I taught a class at Honeywell in Minneapolis. Back in the 1950's and 60's my Dad did some rebuilding at that plant and taught their men how to rebuild. I knew that but did not know they had bought a set of his straight-edges. So in 2008 I got a call from them and asked to come and teach a class there as like many companies they got away from rebuilding machines when people retired or left the company as this happened to Honeywell all those old timers my dad taught were long gone.

The first day of the class I asked them if they had any straight-edges we could touch up as a project for the class? One of the students said there were a bunch of them in a closet behind one of the maintenance shops milling machines. We had to move the bridgeport to open the door.

The foreman said that that door hadn't been opened in 20 year he had worked there. We opened the door and were shocked. There was about 15 straight-edges in there hanging from eyebolts. They had a thick oil on them and dusty as heck. We pulled out the HK-72 out first. That is a 72" camel back with no angle. Looks like your 72" Challenge. We cleaned it, lightly stoned it and set it on a blued surface plate and it hinged perfect and when we flipped it over it was as good as the day they hung it up in there. We then pulled out the others and they were also perfect.

That is the day I started to hang my straight edges from an eyebolt and tell people to hang them. Rich

Pictures are KingWay SE's. The one set is in my station wagon I just brought back from machine shop that were sent to Norway. The SE's shown in the Denmark You Tube. I make Camelbacks with and with-out 45 degree angles. The others are castings I have made and another one I have machined.

 

[wcunning]

I'm still a bit confused as to the balance point you mentioned, Rich?

I did try to look up the spec, but had a bit of a confusion regarding thread depth/engagement vs. rigidity in cast iron. I get that an eyebolt is good enough to pick up a machine from, but I'm less than certain of the strength of the castings of straight edges that already have chips and cracks off of parts. Particularly when I don't see a spot that I'm sure I can drill with lots of meat around it after tapping.

All of that said, I'd like to reiterate my original question: is it possible to check flatness of a longer part (6ft camelback) from a shorter master (5ft granite parallel)? If so, what is the procedure for doing so? I don't see one definitively laid out in Connelly, though I do see hints that it should be possible.

Thanks,
Will

 

[Rex Walters]

Hi, Rich. Looking forward to seeing you again soon. Now that I’m about to start scraping in one of your 36” straightedges, I need to start thinking about storing it.

Like Will, I’m not 100% sure I understood your description of where to put the eyebolt. Let me know if I’ve got it right:

The goal is to put an eyebolt in one end of the straightedge so that it hangs as vertically as possible. Put the straightedge on its side on a bench. Then put a pipe underneath it as long as the straightedge and parallel to the long dimension. Find and mark on the end of the straightedge where it balances across the short dimension. Drill and tap in the center at the marked location for eyebolt.

Cheers,
—
Rex

 

[Richard King 2]

Have to be a detective again. First set the Granite on the Airy points or 30% from each end. What works good in a pinch is Jorgenson 12" 2 screw wood clamps. 2 of them and C -Clamp them to a table. Then clean the granite and cast iron, stone the SE and use a single edge razor blade and a couple squirtrs of windex to lightly go over the granite then wipe with a white cloth or paper towel until it wipes clean white on white.

Then wipe SE and Granite with you hand. Pick up the SE alone or get some help and slowly set the SE down and listen as it sits down. If there is dirt on it you will hear a noise like sand under a shoe. If there is no sound set it down centering SE on Granite If it's a 72" SE and a 60" granite 6 inches will hang out on each side. Hopefully the granite is wider then the SE. now carefully hinge the SE on the granite looking for the rotation points or hinge points on each end. mark that spot. Then cut 3 same thickness shim stocks, say .002" thick. Either plastic or steel like 1/2" wide Precision Brand ona roll.

Then lift one end at a time and slide in a feeler under the rotation point. then take the 3 rd feeler and slide around the SE looking of feeling for gaps. Mark them, if there are not any then carefully slide (one side at a time) the SE so each end and check the ends. Depending on what you see you can get a game plan as to where the lowest points are on the SE. I always scrape the lowest area first and after that 60" area is flat and about 20 PPI I do the other 12". Then after you get 20 PPI on everything and it hinges or rotates in the same places you do it again and get 40PPI. Never slide the longer SE back and forth like your sawing wood as this could give you false readings. when you blue up the first 60" make sure to keep the one end 2" from the end and never let it move over the edge. rub it about 2 " each way. Be sure to ring it a few time while scraping it.

The reason we ring it is when your using it when your done and didn't ring it and it gets bumped accidentally it could ring like a tuning fork and and twist. It's a precautionary step.

 

[Richard King 2]

Rex you you have a way with words...thanks....and if your uncomfortable using a 1/4 inch, use a 3/8" industrial grade eye bolt, not a hardware store eyebolt. Be sure to drill it in the nearest mass. Be a detective as I can't look into a crystal ball and say her 1" in and 2", up..
Rex how about you start a new thread showing where and how you did it, please. Rex just bought one of my HKA-36" castings he had John York milled it. Rich

PS: Rex took one of the Keith Rucker scraping classes I taught last spring i think it was..