Making a new arbor for a Delta/Crescent 12-14 Saw

Modified on 2008/04/05 07:41 by Administrator Categorized as Restoration Topics
''By [http://www.owwm.com/members/detail.aspx?id=11|Keith S. Rucker]''
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==Introduction==
In the Winter of 2004, I was fortunate enough to score a nice old Delta / Crescent 12"-14" Table Saw. This table saw is considered by many to be the best saw that Delta ever made. When Delta introduced the Unisaw in the late 1930's, they immediately realized that they had a winner in the overall design of the saw. Many customers wished for a larger version of the saw so Delta took the basic design features and scaled it up to a larger 12" table saw. The reason that the saw is referred to as a 12/14 saw is that while the saw was originally designed to run a 12" blade, it was soon discovered that the machine could actually hold a larger 14" blade. While the 14" blade cannot be completely lowered below the top of the table, the machine could easily handle the extra capacity.

Interestingly, when Delta first began manufacturing the 12-14 saw, management decided to manufacture the machine at the    Crescent Machine Company factory in Leetonia, OH which had been purchased by Rockwell just as Delta had been purchased in the early to mid 1940's. Even though the design of the saw is all Delta, early machines were badged as being both Delta and Crescent. My saw is one of these early models with the dual manufacturers on the saw. One badge on the front reads both Delta and Crescent while the serial number tag reads Rockwell Manufacturing Company.

When I obtained my 12-14, I was very eager to begin restoring the machine to like new condition. I was fortunate in that the saw was pretty much complete with original parts. The only major problem that I had is that the arbor in this saw was the original arbor with a 1 1/8" shank. While the 1 1/8" size was standard for a 12" and 14" saw blade when this machine was made in the early 1950's, the modern standard is a 1" hole. Even though my saw had the 1 1/8" arbor, I did not think that this was a major problem because Delta had engineered this saw to have interchangeable "arbor extensions" so that the user could have arbors with different diameters as well as different lengths to handle wide dado stacks. To change arbor extensions, all that the user would have to do is purchase the appropriate arbor extension, remove the existing arbor extension in the saw and screw in the arbor extension needed.

==Arbor Extensions==
[imageauto|''Arbor Comparison''|{UP}1214NewArbor/arbor1.jpg]

The original arbor extension options from Delta were as follows:

* No. 34-942 - Arbor Extension with 7/16 Hexagon Wrench, 1 1/8" Diameter, for use with Moulding Cutter Head and up to 1 1/16" Dado Head.

* No. 34-943 - Arbor Extension with 7/16 Hexagon Wrench, 1 1/8" Diameter, for use with Moulding Cutter Head and up to 2 " Dado Head.

* No. 34-947 - Arbor Extension with Special Arbor Flange and Nut, 1" Diameter, for use with Saw Blades.

* No. 34-948 - Arbor Extension with Special Arbor Flange and Nut, 1 1/4 " Diameter, for use with Saw Blades.

* No. 34-949 - Arbor Extension with Special Arbor Flange and Nut, 1" Diameter, for use with Moulding Cutter Head and up to 2 " Dado Head.

* No. 34-950 - Arbor Extension with Special Arbor Flange and Nut, 1 1/4 " Diameter, for use with Moulding Cutter Head and up to 2 " Dado Head.

==Making a New Arbor==
My first step was to purchase a 1" arbor extension for my saw. From what I understand, the only arbor extension that is still available from Delta is the No. 34-947, 1" Diameter arbor extension for use with regular saw blades. While I did not actually price this part from Delta, I am told that it is very expensive - just the nut for this extension cost over $80.00. Instead of buying a Delta original, I did some searching and discovered that Grizzly made a 14" table saw that appeared to be a very close copy to the Delta 12-14 saw - at least on the inside of the saw. This saw used a very similar looking arbor extension system where one could change out the extensions for regular saw blades, dados and even different size arbors. Taking a chance, I called Grizzly to see how much their 1" diameter Dado Extension would cost. To my surprise, the price was very reasonable - a little over $20 for the dado arbor extension, $4 for the nut and another $4 for the flange. Since the price was not too high, I ordered the set in hopes of it fitting my Delta saw.

[imageauto|''The Grizzly 1" Dia. Dado Arbor Extension with Nut and Flange.''|{UP}1214NewArbor%2fgrizzly.JPG]

All that was left for me to do was remove the original arbor extension from the saw and try to replace it with the one from Grizzly. When I tried to remove the original arbor extension from the saw, it would not come loose. I tried and tried but no matter how hard I tried, it just would not break loose from the arbor. Since I was planning on replacing the bearings on the arbor anyway (they appeared to be the original bearings that came with the saw and were over 50 years old), I just removed the whole arbor and arbor extension from the saw. I then took it by a friends shop who is an agricultural equipment mechanic. If anybody could get the arbor extension off, he could. After about an hour of trying everything under the sun, we both gave up. The arbor extension was not coming out.

So, I decided to go to Plan B. I called Delta, gave them the part number for a new arbor for the saw and gritted my teeth waiting for the price. As much as I hated to spend money on a new arbor, that appeared to be the only option at this point. I figured that the price for a new arbor would not be less than $100 and I was prepared to pay as much as $200 for a new arbor. Imagine the surprise when the nice person on the other end of the telephone responded that the new arbor assembly for my saw would cost me $410.00 plus shipping. It took me a few seconds to pick myself up off of the floor. When I finally got the phone back up to my ear, I nicely told the lady that I would just have to do something different. Heck, that was nearly half of what I paid for the entire saw!

I spent the next day or so just mulling the whole thing over. To tell you the truth, I actually spent some more time trying to remove the arbor extension from the original arbor but try as I might, it still was not going to come out. There was only one thing left to do - I would just have to make a new arbor for this saw myself.

[imageauto|''The original arbor''|{UP}1214NewArbor%2foriginalarbor.jpg]

Fortunately for me, when I graduated from high school in 1986, I spent two years working as an apprentice in a machine shop before earning enough money to begin going to college. During my machine shop days, I spent most of my time making single and small runs of prototype parts for varying engineering companies and most of the work I did was lathe work. While this arbor is not even close to some of the more difficult parts that I made back when I worked in the machine shop, it had been nearly 15 years since I had done any major work on a lathe. I had purchased a 10" Logan metal lathe about six months earlier in the year but I really had not had an opportunity to use it for much of anything. To say the least, I was worried that my skills as a machinist were not up to snuff for this project.

After deciding to make a new arbor, the first order of business was to find an appropriate piece of steel to make the new arbor from. From what I could tell, it appears that the original was made from a single piece of steel - probably drop forged to produce the large flange in which the saw blade rides against. Finding a drop forged blank was pretty much out of the question so a piece of bar stock would have to do. While the original piece appears to be one solid piece of steel, I really did not want to have to machine this arbor from a piece of 3" diameter bar stock. To make life easier, I decided to machine the main shaft from a piece of 1 1/4" Cold Roll Steel and then machine the flange from a short piece of 3" Cold Roll Steel. I would bore a hole in the flange that was slightly smaller in diameter than the smaller shaft and then press the two pieces together and then weld them to make sure that they did not ever come apart.

The basic machining of the main shaft was pretty straight forward. Using the original arbor as a guide, I machined the four steps of the shaft to the proper size, keeping tolerances very close to the original.

[imageauto|''Machining the main shaft''|{UP}1214NewArbor%2flathe.JPG]

All went very well until it was time to cut the threads on two of the steps of the arbor on which a nut that would screw to hold the two bearings in place. Both of these threads were to be cut to 24 TPI to fit the nuts that was on the original arbor. This was my first big hurdle to jump. When I purchased my lathe, the seller told me that it came with a complete set of change gears except for one which was missing when he purchased the lathe. He could not remember which size thread this change gear was needed to cut but he did say that it was a size he had never needed. Of course, the first time I would use my lathe to cut threads, you can guess which change gear I needed.

The next morning, I called Logan and ordered the change gear. It set me back about $100 but heck, I needed the gear anyway. At least that is what I kept telling myself. It took several days for the gear to arrive in the mail and when it finally did, I promptly got back in the shop and cut the threads on the arbor. Once these threads were cut, I was through with that side of the shaft so I removed everything from the lathe.

The next step was to make the flange. I visited a friend that I go to church with that owns a metal fabrication business and he gladly gave me a short piece of 3" diameter steel to make the flange from. I chucked this up in the lathe and drilled the largest hole in which I had a drill bit for. After that, using a boring bar, I bored the inside diameter of the flange to 0.0005" smaller than the diameter of the area on the arbor the flange would be pressed. After the hole was bored, I machined the profile of the back side of the flange. The face of the flange on which the saw blade would go against was left thicker then was needed - this would be machined after being pressed and welded on the arbor so that it was true to the rest of the arbor.

[imageauto|''The arbor and flange (middle) before being pressed together. The original arbor is above and the arbor extension below.''|{UP}1214NewArbor%2farbor1.jpg]

[imageauto|''The arbor and flange before pressing together.''|{UP}1214NewArbor%2farbor2.jpg]

Before pressing the arbor and flange together, I first had to drill two holes in the flange like the original arbor. The two holes are for a special spanner wrench which fits into the two holes and holds the entire arbor from turning while changing out arbor extensions. To do this, I again visited my ag mechanic friend who has a milling machine is his shop which he lets me use when I need it. I carefully found the center of the flange using an edge finder on the mill and then drilled the two holes in their proper location. While I was at the mill, I also went ahead and milled the key way slot in the arbor which would hold the belt pulley in place. After the two milling operations were complete, I used a hydraulic press and pressed the flange onto the arbor and then let a professional welder who worked in the shop weld the two pieces together. I next went ahead and pressed the front bearing onto the arbor while I had access to the hydraulic press.

The arbor was really staring to take shape now. All that was left to do was bore and tap the hole in the arbor to fit the arbor extension. The entire piece of work was once again chucked into the lathe and a steady rest was used to keep the arbor running true while boring the hole into the end of the arbor. A hole was first drilled to the size needed for the inside tapped portion of the hole. Then a taper was bored at 15 degrees to match the taper on the arbor extension. Once the taper was bored to the correct diameter, the hole was tapped with a 5/8" Left Hand Thread tap to accept the threads of the arbor extension. The final step was to face the flange so that it was true to the arbor.

[imageauto|''The finished arbor (bottom) with bearing and arbor extension installed. Original arbor above.''|{UP}1214NewArbor%2farbor3.jpg]

[imageauto|''End view of finished arbor (left) next to the original arbor (right).''|{UP}1214NewArbor%2farbor5.jpg]

The project was drawing near an end. I next put the arbor back in the saw, putting the belt pulley and belts in place as well as putting the back bearing and retainer nut on. The final test was to put a saw blade on the new arbor and check for run out. To my amazement, run out was less than 0.001".

[imageauto|''The finished arbor installed on the saw.''|{UP}1214NewArbor%2finstalled1.JPG]

All in all, the whole project took me a little over two weeks to complete. My schedule was so busy during this period that I only had time to work on the project from 15 min to an hour at a time - a challenge that made the whole process slow and sometimes hard to follow. I also found myself often stopped for a day or two at a time as I determined that I needed special tooling which had to be ordered and shipped to me before continuing on to the next step. I figured that all in all, I had about 10 hours of labor in this project - a seasoned machinist could have probably done it much faster but I was working slow as I was brushing up my lathe skills the entire time I was working on the project. Also, if truth is told, I probably have more than the $410 that a new arbor would have cost me in making the new arbor - most of which was spent on tooling for my lathe that did not come with it when I purchased it. While the arbor I made may have cost me more money out of pocket than buying a new one from Delta, I feel like I am much better off having made my own as the money spent was invested in tooling that can be used for many years to come on future lathe projects. Best of all, the project helped me to revive some skills that I had learned many years ago on operating a metal lathe that were all but lost due to lack of practice. In the end, a very rewarding job in more ways than one.
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