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 Post subject: Low Cost DIY Reamer
PostPosted: December 21, 2021, 10:58 pm 
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Always Moore!
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Joined: November 9, 2007, 3:40 pm
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Location: Pittsburgh, PA
Earlier this year I had to replace a set of bushings on a Sprite spindle. The bushings have to be line reamed to size after install. Reamers are sort of commercially available but expensive ($300-1000). I knew of one or two vendors that allegedly did the service but it seemed worth trying the DIY route first since there are several of these cars within the circle.

I started with a piece of annealed W1 bar stock, added a hex for a wrench, and turned the soon-to-be cutting surfaces to 0.0005"-0.001" larger than the journal.

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I first drew the flutes in CAD to help get the spacing correct. Next they were cut using a 1/2" carbide endmill.
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I initially added a small pilot at the start of each reamer in the hopes that this would create enough of a cutting surface. The first attempt failed and it was back into the lathe. I removed more material and hand sharpened the flute tips with a file. A quick test yielded some chips so this seemed like it had a chance of working.

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The last step was to heat each flute until orange started appearing and swishing it around in water. Following hardening, everything was annealed to remove some brittleness.

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And for the moment of truth.....

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I'm calling it a success. I am still not sure how it would work on harder materials but this process definitely works for softer stuff like aluminum, brass, and bronze.


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 Post subject: Re: Locost DIY Reamer
PostPosted: December 22, 2021, 7:19 am 
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Joined: April 23, 2019, 4:30 am
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Location: New Zealand
A thing of beauty, solid principles well executed - a superb example of keeping craftsmanship alive, thanks for documenting. :cheers:


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 Post subject: Re: Low Cost DIY Reamer
PostPosted: December 22, 2021, 10:38 am 
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Joined: July 7, 2011, 12:17 am
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Location: Oregon City, OR
Nice work! Did it change dimensionally at all after heat treating?

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 Post subject: Re: Low Cost DIY Reamer
PostPosted: December 22, 2021, 12:46 pm 
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Joined: October 24, 2008, 2:13 pm
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Location: Carlsbad, California, USA
Impressive!

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

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 Post subject: Re: Low Cost DIY Reamer
PostPosted: December 22, 2021, 4:53 pm 
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Always Moore!
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Location: Pittsburgh, PA
Thanks guys.

RTz wrote:
Nice work! Did it change dimensionally at all after heat treating?


I checked a few diameters and didn't notice anything but if I keep running into projects like this, I'll probably get a toolpost grinder to make finishing easier. I did some stubshafts for a friend a few years ago and they definitely grew about 0.001"/1".

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 Post subject: Re: Low Cost DIY Reamer
PostPosted: December 23, 2021, 12:14 pm 
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Joined: April 26, 2008, 6:06 pm
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Fantastic work! :cheers:

On the one hand, it would be interesting to get a full measure on the tolerances you achieved... On the other hand it probably doesn't really matter, because it's likely as good or better than what it came out of the BMC factory with. :mrgreen:

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 Post subject: Re: Low Cost DIY Reamer
PostPosted: December 26, 2021, 10:46 am 
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Always Moore!
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Joined: November 9, 2007, 3:40 pm
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Location: Pittsburgh, PA
After tearing into many A-Series engines, Spridget transmissions, and Spridget rear ends, it is clear why they did not succeed. I can respect that they didn't have automation available back then but there is no evidence of a functioning QC or QA department.

Cut it too deep? Measure to figure out how much and shove some more shims in there.

Made the bore too big? Go to the oversized piston shelf and pick one.

Machined the faces too far apart? You have an assortment of thrust washer thicknesses to make it right.

There is no way they made up for the labor cost with what they saved in salvaging parts that were at the far end of a tolerance. Even having to install a LSD can be a chore since there was a special gauge block set but it hasn't been made for decades, only dealers had them, and no where have I seen the block thicknesses published. As luck would have it, these housings are probably the most poorly machined piece on the entire vehicle so there are shims everywhere. I had to measure several untouched diffs and make a judgement call.

So I'm with you - my homemade tool is probably no worse than what was used in production.

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 Post subject: Re: Low Cost DIY Reamer
PostPosted: December 26, 2021, 4:20 pm 
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Joined: January 2, 2009, 1:45 pm
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Location: Halifax, Nova Scotia
Andrew, when I was growing up we had a 1956 Morris Oxford Traveler with a 1500cc B series engine. The car was an oddity for BMC in that it had torsion bar front suspension and real (i.e. tubular ) shocks. My dad did most of his own maintenance and had his own shop manual, in the days when the shop manuals were just that. My memory is that the 'pick the part to suit the space available' philosophy was institutionalized in the manual.

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 Post subject: Re: Low Cost DIY Reamer
PostPosted: January 1, 2022, 3:05 pm 
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Joined: January 31, 2008, 5:34 pm
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Location: SW Wes Consin
Very nice!


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