Morgan Hand Mill Strip Measurement.

[snorider]

The pith and fuzz make the morgan measuring block inaccurate and even after cleaning up the strips it is not very accurate. A friend has suggested measuring the width as it was milled clean and harder, and it does work well. Took a bit of Trig but these conversions seem to work.

Measure the base width, you can do this on the anvil which is nice. Divide that number by 2. Take the result and divide by: .7467 (Penta) .5949(Hex) or 1.0355 quad. These numbers are based on the actual angles of the MMH cutter heads.

I considered this as half the strip forming a right triangle. From the cutter head we know the vertex angle of the strip. Divide that by two and we have A, the top angle of the right triangle. TanA=opp/adj and we know that opp=1/2 the width of the strip base. SO Adj (height) = (width/ 2)/Tan A. Just wanted to share as this makes measuring much easier for me.
Cheers,
Michael

[BigTJ]

My experience and experience of many other hand mill users are the opposite. There is loads of info on the internet about vblock accuracy. Plus the guys at Tom Morgan Rod smiths are great. If you give them a call they can help you figure it out. My guess is that something is haywire with your offset. You are offsetting the caliper reading by about 0.0115 for a hex right?

The most accurate way to check strip dimensions I’m aware of is to bundle them and take a flat to flat measurement when they are 5 or 10 thou from final. Don’t forget to knock the apex off first. Tape them every 6-8”.

Using trig to estimate the height could lead to errors. Do you have some data from finished rods to show this produced repeatable and accurate results?

John

[Canewrap]

+1 to what John said.

[Tim Anderson]

I have used the Waara-style MHM measuring block for the entire time I have used a Morgan Hand Mill and my experience is that the results are very precise and reproducible. Absolute accuracy depends on the zero setting of your calipers and on the relative humidity in the cane.

The "chimney" left by the mill's cutters does need to be removed before measuring with a measuring block. I have experimented with various ways to remove it and, over the last several years, have used a small bullnose plane with some guides glued to the base. Works for me.

Tim

[WIHEXROD]

There are many ways to measure strips. Pick one that works for you. I showed several ways during the VRG on the MHM.

Tom Morgan Rodsmiths put together a youtube on using the measuring block.
https://www.youtube.com/watch?v=gn4gfUdxEnY

They have several new videos, well worth the time to review.
https://www.youtube.com/channel/UCGwJ9t ... czyJEm0zjQ

Scott

[snorider]

Oh I am sure there are multiple accurate ways to do this with the block, and I do have Tom's manual. Plus I can bike to Morgan Rod Smiths in about 3min from my house, they are great guys.

I am new to building rods, but my good friend is a very long time and somewhat famous rod builder and you know he is right it's easier. I can measure strips on the mill, calculate the strip height and it translates to the finished blank size so I'm happy. Your milage of course may vary.

Thanks Guys.
Michael

[WIHEXROD]

Michael,
There should be an Excel spreadsheet in the manual that shows the height of a strip based on its width.
You might just compare the numbers to yours.
Scott

Remember the thickness of the glued section will not be the sum of the heights of the two strips. The apexes do not touch.

[BigTJ]

It’s hard to be sure your buddy is right or if even matters who is “right”. There are almost more than one best way to do things in rodmaking it just depends on the person. Marty Karstetter is the guy who convinced me to use the vblock and putting strips together to measure flat to flat as a qa step and it has worked out pretty well. My first attempts with the vblock were failed like yours but after a second go at it I figured it out and it clicked. All that matters is that it works for you. I can definitively say it is wrong that the Morgan vblock isn’t an accurate way to measure strips when it is done properly.

I am now having a memory that the width to height relationship was something Lew Stoner did. Maybe Doug Merrick and the rest of the Winston gang not sure.

John

[BigTJ]

Michael,

Remember the thickness of the glued section will not be the sum of the heights of the two strips. The apexes do not touch.

Super important concept for hitting numbers on a hand mill.

You have to match the flat to flat / 2, not the strip height.

The thicker the section the more it matters. Learned that fast on my first MHM made rod. Experience is a valuable teacher.

John

[Tim Anderson]

Measuring the strip width of MHM-produced strips can give you a better result if you forget that the 61.5° cutter head (hex rods) will give you a strip that is not as high as 1/2 the flat-to-flat taper indicates. The 61.5° strip height is very close to 97% of 1/2 of the flat-to-flat number. Because it's a percentage, the difference in thousandths of an inch increases toward the butt. The dimensions of the finished blank depend on the strip width.

I incorporate the 97% in my spreadsheet to calculate the anvil rise of my MHM.

Tim

[Anders Johannesson]

The MHM v block is a very good tool. But there are something to bear in mind.

1. the v block does not have the same angle as the cutterhead which will give a very small deviation i math. regardless of 60,5 or 61,5.

2. for measuring strips it is also a part of the root cause if the enamel surface is flat or has a radius. If the enamel i scraped to total flatness the width of the strip vill be larger than for a strip which is not that flattened for the same height

3 regardless of which cutterhead angle used the strip will have the contact point at the corners closest to the outer fibers.

4. when measuring with a micrometer with a 60 degree grove and the MHM in 61 it will not give the same measuring

5. however - there is no such ting as exact and the symmetri of a rod is of course always more important than the absolute dimension. Humidity, temperature, bamboo etc

6. The bed of the mill, the anvil, clearance between plane and bed, precision in the butterhead is good but can in theory have som impact

7. the cylindrical gauge delivered with the hand mill was far away from round. My recommendation get a gauge pin in the correct dimension and make the setting and you will have a home run!

8. I strongly recommends to make 6 strips untapered measure them. Glue them up. Measure flat to flat what you get and set the caliper with the v block. In addition it can be wise to measure that joint in the winter and in the summer and see the difference.

[trland]

I incorporate the 97% in my spreadsheet to calculate the anvil rise of my MHM.

Could you elaborate on this a bit?

[Tim Anderson]

I incorporate the 97% in my spreadsheet to calculate the anvil rise of my MHM.

Could you elaborate on this a bit?

The anvil rise is determined by the height of the strip. If the 61.5° cutters are used and the MHM 61.5° measuring block is used to measure the strip height, the measured strip height (ignoring the curvature or flatness of the enamel side) will be very close to 97% of 1/2 the flat-to-flat dimension of the desired taper. So, the anvil rise I calculate with my spreadsheet is based on 97% of 1/2 the flat-to-flat taper. What some might call anal-retentive measuring of strips and blanks has confirmed the validity of this approach for me. Others may find incorporating the 97% to be unimportant.

Tim

[Canewrap]

"the v block does not have the same angle as the cutterhead which will give a very small deviation i math."

Anders, the V-block that TMR supplies does have the 61.5 angle in the center of the measuring block. I use it all the time and get accurate readings.

-Bill

[Canewrap]

I incorporate the 97% in my spreadsheet to calculate the anvil rise of my MHM.

Could you elaborate on this a bit?

The anvil rise is determined by the height of the strip. If the 61.5° cutters are used and the MHM 61.5° measuring block is used to measure the strip height, the measured strip height (ignoring the curvature or flatness of the enamel side) will be very close to 97% of 1/2 the flat-to-flat dimension of the desired taper. So, the anvil rise I calculate with my spreadsheet is based on 97% of 1/2 the flat-to-flat taper. What some might call anal-retentive measuring of strips and blanks has confirmed the validity of this approach for me. Others may find incorporating the 97% to be unimportant.

Tim

I actually find it to be unimportant, unless you are factoring in the glue-line and even then the glue line isn't always exact either. I've tried factoring in the 97% of target and I just wound up undersized, just my experience YMMV.

[trland]

The anvil rise is determined by the height of the strip. If the 61.5° cutters are used and the MHM 61.5° measuring block is used to measure the strip height, the measured strip height (ignoring the curvature or flatness of the enamel side) will be very close to 97% of 1/2 the flat-to-flat dimension of the desired taper. So, the anvil rise I calculate with my spreadsheet is based on 97% of 1/2 the flat-to-flat taper. What some might call anal-retentive measuring of strips and blanks has confirmed the validity of this approach for me. Others may find incorporating the 97% to be unimportant.

Tim

Thanks Tim. That's very helpful. I'm going to plug that in to some previous taper builds and see what the differences are.

Mike

[Anders Johannesson]

The V -block from Tom which I have is marked 61. The difference is at the end of the day unimportant. But it can be confusing if using different tools to measure.

At the time of purchase the hand mill I made a phone call to Tom and he recommended my the 61,5 cutter head. He had used the design for decades. How ever I have found that the joints made by me made with a 60 degree head gives me much better FtF(flat to flat) dimensions.

Regardless of the angle used the ones by MHM or your own choice it will in theory always be the width of the strips that gives the FtF. But, and there is always a but, if all strips are perfectly centered - and that is far away from the result in many cases.

As far as I can se the height of approx 97% is only important if you are measuring the strip without the V block. The strip will have the contact point att the outer edges.

I have had my 61,5 cutter head in the tool box for retired items.