Tag Archives: Van Norman boring bar

Engine Cylinder Bore Machining – Cylinder Regrinding and Reboring

After finding this entertaining photo taken in Freeport, Maine and having been in the machining and engine rebuilding business for a number of years, we thought this would be a good time to show you how cylinder regrinding and reboring was done back in the period and today.

The Freeport Engine Co. may have used a cylinder grinding machine similar to the one seen below. The Madison Cylinder Grinder and it’s description, show the type of machine which was used out in the field for a precision oversize regrinding job. This type of machine was used as late as the post-WWII days by some shops.

              

It’s called an i.d. grinder because it is used for grinding the inside diameter of a bore. An o.d. grinder, like a crankshaft grinder, finishes the outside diameter of a workpiece. In the hands of a skilled machinist, a cylinder grinder, as seen below, produced an excellent job with a fine finish. It also assured that the cylinder bore ended up being at a perfect right angle to the crankshaft, a very important factor.  The photo of the Freeport Engine Co. is courtesy of the Leslie Jones Collection at the Boston Public Library.  The advertisement (above), is from volume 25 of the 1921 Cycle and Automobile Trade Journal.

In contrast to the grinding machine, the six advertisements (below) show the progression of cylinder boring machines that were offered to the garage and automotive machine shop trade over the years and shown. The portable boring machine went on to become the standard of the industry by the mid 1930′s when high quality and extremely accurate machines entered the market. This type of machine is still used today by many shops.

               

L to R, above ; The Heiser was one of the earliest machines of this type. From the Feb. 1918, Motor Age. The ad for Dunn was found in the Motor Age during 1920, and the Wepplo was the first of the electric motor-driven machines and dates from 1922. 

               

L to R, above; The Simplicity (1929) was a combination boring-grinding machine offered by the company that later offered a full line of automotive machine shop equipment in the 1930′s. The Storm was one of the first automatic machines offered by the company. They went on to develop and market a full line of machine shop equipment. Last is the Van Norman “Perfecto”  from 1936). It set the standard for this type of machine and was offered in several different sizes through the 1960′s.

The best, but not the quickest way to handle the job today, is to rebore a cylinder first with a boring bar and then finish it off by honing to the final finish size. Below are photos of the reboring of a “T”-head Mercer cylinder block that we did here in the shop with one of our two Van Norman boring bars (a large model 888 “Jumbo Perfecto”). This machine will bore cylinders up to 7.5 inches in diameter and 18 inches deep. If you are interested you can learn more about how cylinder reboring and honing is done by visiting two posts that we did for Hemming’s Daily. They will give you an idea of what is involved in the process.

               

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