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Sanding allowance?

How much to allow?

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#1 River Rat

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Posted 07 July 2015 - 03:44 PM

I've been thinking about increasing the depth of my splines to allow for some material removal during sanding and wonder what you folks have been doing.  I've been reducing the spline depths by 0.001" to allow for the glue as recommended in Cane Rods Tips and Tapers  by Ray Gould but I often find that the section winds up slightly smaller at each station when I'm done with final sanding.  On my latest rod I checked the section depth at each station before gluing.  I use Epon and clean the section by lightly scraping (no bamboo removal) about 36 hours after gluing and then rebind and heat set so not much sanding is required.  Usually I'll take 3 strokes on each face with 220, 320 and lately 600 and there was a noticeable reduction in the depths at the stations and wonder if anyone has any advice as to how much to allow initially.  Certainly the 0.001" glue allowances are going away.

 

Thanks,

Cliff


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If it's worth your time to do, it's worth doing to the best of your ability.


#2 Galt

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Posted 07 July 2015 - 10:08 PM

Cliff,

 

 If you were to measure your stations before and after sanding, you would have an idea how much you might be removing. Adjust your spline dimensions accordingly. If after sanding, your measurments are the same as before sanding but your station dimensions are off, adjust youe spline dimensions accordingly. It doesn't matter what others are doing for allowances. What matters is what works with your proceedure. If your process is consistant and you are regulary missing your target by a consistant amount, the amount of correction should be evident.

 

Galt


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#3 Tim Anderson

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Posted 08 July 2015 - 12:47 PM

I agree with Galt.  Follow your usual procedures and adjust your dimensions to have the completed blank measure correctly.  If you later change your procedures, you will know what effect the changes have or don't have.

 

I personally do a lot of measuring during strip cutting and of the completed blank.  Most of my rod making friends think what I do is excessive, but the results have been very instructive for me.

 

Tim



#4 River Rat

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Posted 10 July 2015 - 06:48 AM

Thanks, I understand the methodology to arrive at a target value.  What I was hoping to find is some sort of experiential suggestion to use as a starting value.  For example, do folks find that 0.002 or 0.003 works well or is that too much  It would seem to me that allowing too much would then require the section to be resized with sandpaper which would be a really difficult thing to perform accurately.  Too many hours are involved in getting to a glued blank to just go at it blindly.

 

Cliff


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If it's worth your time to do, it's worth doing to the best of your ability.


#5 Galt

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Posted 10 July 2015 - 03:45 PM

Please don't take what I am about to say as harsh. You have the capability to determine the EXACT sanding allowance for your methodes . You described your proceedure with the three grits. Take 10 scraps and go through your proceedure and record the before and after measurements. Do this for scrap representing butt strip widths and for pieces representing tip widths. If you are consistant in your pruceedure, each group of measurements should be close. Take the average and use that as the allowance for that size strip. It is likely the allowance will vary from tip to butt. If your group measurements are not consistent, work on making your proceedure more consistant through developing your sanding skills.

 

The theoretical sanding allowance should be '0' as you would only remove the excess adhesive and stop at the cane surface.

 

I am not sure how a third party's allowance would be applicable to your individual situation. A third party allowance or your own guess would be about the same. You wouls still have to measure when finished and adjust the allowance again until youe measurements agreed with your allowance. There is no real substitute for consistancy of method and percision of measurement to achieve accurate results.

 

As to missing the target dimensions, according to Bob Milward, slightly over sizing and finishing to target dimension is a lesser 'sin' than under sizing.

 

Galt


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#6 Canewrap

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Posted 30 July 2015 - 09:39 PM

Are you sanding after you've already removed the glue? Is this to remove enamel? I do all my enamel removal before I get to final dimensions. I cut each strip ~.002 under final to allow for glue up, it allows the strips to sit better in the forms. A fairly flat enamel side is critical to getting good dimensions. The curve of the enamel side will give you undersized sections when you start flattening out the enamel.



#7 River Rat

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Posted 06 August 2015 - 09:30 AM

Been away for a while.  Canewrap, I glue with Epon and have removed the enamel before gluing.  Before heat-setting the glue I lightly scrape the blank with a cabinet scraper trying very hard not to get into the 'boo.  The sanding is minimal as described in my original query above, and occurs after the heat-setting step.  The unglued blank generally hits the specified taper dimensions.


Cliff Parmer

If it's worth your time to do, it's worth doing to the best of your ability.


#8 River Rat

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Posted 06 December 2015 - 07:31 PM

To finish this topic out, I've been experimenting with how much to allow for sanding and found that about 0.002" per strip works well enough.  I've found that I have to do some sanding to get the section dimensions to the taper but that beats the heck out of finding that it's too @#$! small.


Cliff Parmer

If it's worth your time to do, it's worth doing to the best of your ability.




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