Marking out material

[Brian Rupnow]

I was asked on another forum, how I do my layout work on the parts I machine. After I typed out my answer, I thought Hmmm---That could be a thread in itself---so here it is.

#1-Laying out material.--I do all my "layout" on the corner of the cheap wooden reference desk in my office. : : :(The same one that most stuff is setting on when I take pictures of it) I do 99% of my layout using my vernier calipers --Laying one jaw against a "finished" edge on stock and setting them to what dimension I want and dragging them along to scribe a line with the offside point. I don't use a digital height gauge---I have one but I find it rather large and awkward to use. On some lines I measure the length fron one end of a part with the Vernier caliper, make a mark same way as in step#1. then use a small machinists square and scriber to make the line. I have two or three sets of good quality compasses left over from my manual drafting days, and on them I have removed the lead from the one tip and replaced it with a second steel tip for drawing circles. I don't have a surface plate.

Aligning lines on parts in the mill---I have a cheap little bubble level about 5" long to maintain "'Horizontality" (I don't think thats a word) when clamping stuff in my vice. Sometimes I just use the inside bottom of the vice itself, or with parallels setting on it and make certain that the part is setting tightly against it.--Although that method isn't great, because the inside bottom of my vice is only about 2" wide, and things will tip. I always ensure that my vice is set "square" to the table, and depend a great deal on the vice to align things clamped in it squarely to the table.

I have an ancient bubble level/protractor square (that I don't even know the correct name for) to set up angles .

If any of the SOB's who owe me money on outstanding engineering invoices ever pay me, I may buy a simple height gauge for doing some of my layout with a surface plate.

I know that a lot of my stuff looks impressive.---Hell, it impresses me!!! But I have a dirty little secret!!! 95% of everything I do is visual, and so consequently only 5% of it is really critical mating surfaces, where finely held tolerances are really important. I try as hard as I can to hold extremely fine tolerances on that 5%. The rest of it is all "plus or minus" ---probably considerably beyond the tolerances allowed for in the drawings, but it LOOKS RIGHT. Just don't pick it up and put a micrometer on it.----Brian

 

[Cedge]

Brian
There is a lot to be said for "looks right"... but I always strictly adhere to the drawing....yeah right.....LOL

Steve

 

[SAM in LA]

Brian,

This is not a dig, I'm just sharing a funny story and you reminded me of it.

The other day I was helping out on one of my boys Eagle project.

One of the dads their told a story about something that "Looks right".


This fellow was building a wagon frame out of wood. Once it was all together he went around it with a pencil and marked all of the joints with a pencil line. When the man he was building the wagon frame for came by to pick it up he noticed that all of the boards were on the lines. He said, "Looks right, all of the boards are on the lines". He was paid a little extra because of the precision work he did.

:big:


SAM

 

[Brian Rupnow]

Brian,

This is not a dig, I'm just sharing a funny story and you reminded me of it.

The other day I was helping out on one of my boys Eagle project.

One of the dads their told a story about something that "Looks right".


This fellow was building a wagon frame out of wood. Once it was all together he went around it with a pencil and marked all of the joints with a pencil line. When the man he was building the wagon frame for came by to pick it up he noticed that all of the boards were on the lines. He said, "Looks right, all of the boards are on the lines". He was paid a little extra because of the precision work he did.

:big:


SAM

;D ;D ;D ;D ;D ;D ;D ;D

 

[jpaul]

Brian,
I am glad you started this thread. I am always looking for other methods to keep me from scrapping parts.

Ninety five percent of the time I dykim my parts and scribe the location of holes trim lines and radii on the part. I do this even though I will be locating these features with travel dials or DRO,s. After laying out lines and holes on the part I visually compare the scribed part to my plan. Have you ever mirrored your part unknowingly?

Often I will use a felt tip marker to identify a dimensions or identify a reference surface directly on the part. At times I will lose layout lines while machining and I will remark the part.

My layout tools are a vernier height gage, a 6" metal rule, dividers, scribes, and circle templates. I have a surface plate but most of the time I reference off a 12" square piece of tile.

 

[Brian Rupnow]

I haven't unintentionally mirrored a part yet, but I have a bit of advantage with 45 years experience as a design engineer, What makes me absolutely crazy (and most everyone else also) is building a left hand part when you have a drawing of the right hand part only and it says "Make one part right hand as shown and one part left hand opposite"---Then you have to turn it all around in your head as you are laying it out. Also, a part drawing which has counterbored holes which are counterbored on the far side to what is shown. Then you again have to turn it all completely around in your head, because you always counterbore from the same side a you drill on.

 

[tornitore45]

I find adjustable parallels very useful for marking out.
Set to the desired distance (minus a couple of thou) and scribe close.
Using the caliper to scribe leaves me unsatisfied, even if is good enough for close work. The jaw does not leave a crisp line and the necessary angle to engage one jaw to one edge makes for a cosine error.

I am not saying I never use the method.

Mauro

 

[doubletop]

Included in the equipment from my fathers workshop was scriber block, a vernier height gauge, surface plate and a set of slip guages. The vernier height gauge was always a challenge to work out what it was set to and it started at 3.5cms so what use was that? So it stayed in its box. I was aware that the slip gauges needed to be looked after but what did I need a set of blocks that allowed increments of .001" from .101" to 4" for anyway? They stayed in the box as well. So all my marking out was done with the sciber block and a ruler and sometimes the digital caliper being set to the length I wanted and then transferred to the sciber block. The sciber block had a fine adjustment knob so it was great,ish.

Then I had an epiphany moment the other week when doing my latest engine.

That sharp pointy wedge shape on the front of the height gauge was a scriber. If I stacked the slip guages up I could accurately set the height gauge to any height I needed. No need to read the vernier. Although they were imperial slip guages any metric height could be set by dividing the metric value by 25.42 and working in inches.

Slip guages

Setting 5cm = 1.967" so slip guages 1", .85" & .117"

Scribe the line using v block to keep job vertical.

Dealing with heights below 3.5cm was easily sorted by use the V block to raise the job

Setting the height

Scribe the line, using a second V block as a support

From now on the scriber block is relegated to the cupboard.

Its simple quick accurate and repeatable. Unfortunately these gauges ain't cheap.

Pete

 

[Cliff]

Brian that is called creative machining. Cliff

 

[doubletop]

Of course a digital height gauge is cheaper and a lot simpler................

 

[dsquire]

That sharp pointy wedge shape on the front of the height gauge was a scriber. If I stacked the slip guages up I could accurately set the height gauge to any height I needed. No need to read the vernier. Although they were imperial slip guages any metric height could be set by dividing the metric value by 25.42 and working in inches.

Pete

Should that not be 25.4 that you divide by instead of 25.42? I know it's not much but if using this kind of equipment for layout you may as well be as accurate as possible. I imagine that this is just one of those things that the spell checker missed.

That looks like some nice equipment that you father left for you. Treasure it and enjoy it and remember him when using it.

Cheers

Don

 

[doubletop]

Don

Thanks for pointing that out I've no idea where I got 25.42 from.

My dad is still around and occasionally watching my antics on this forum. He gave me the kit as his sight was failing.

Pete

 

[Blogwitch]

Even though I use DRO's, I always like to blue up and mark out if possible. It gives a double check against making mistakes.

Also, if you can learn to use a good height gauge and marking out equipment, and you can pick up how to machine to 'splitting the line', you can easily achieve 0.002" (0.05mm) accuracy, and most times 0.001" (0.025mm). Plenty good enough for the types of things we do. A scibed line off a height gauge is usually about 0.002" (0.05mm) wide.

Until my eyes started to fail, that was the way I had done it, and a lot of other people as well over the years.

There is nothing new in this method of operation, all thru the industrial revolution up until precision measuring instruments came along for the masses, everything was done this way. Scribe a line, double check it, then machine to it. Unless you try it out yourself, you don't realise just how fast the system is to get something to size (or near enough).


Bogs

 

[stefang]

Even though I use DRO's

Even with CNC, I prefer to do manual marking first..helps to get a feel for the part, and also minimizes the chance of putting the part in a wrong way into the vice...

Stefan