Chainsaw Bar Mounts

If you look at your chainsaw, the area where the chainsaw bar fits to the body of the saw is called the “bar mount” or “bar mount pad”. While most bar mounts look alike there are some major differences that prevent proper fit up and oiling if the saw’s bar mount pad and chainsaw bar mount don’t match.

Chainsaw Bar Assembly

The chainsaw’s bar mount incorporates the mounting slot (where the bar studs fit through the bar), the bar adjuster pin hole (in most cases) and the chain oiler holes. Most chainsaws use a bar adjuster assembly consisting of a screw and bar pin located in the bar mount pad. Turning the screw allows the bar pin to move forward or backward in the bar mount pad which moves the bar forward or backward in turn tightening or loosening the saw chain.

Some Oregon brand chain saw bars utilize the “intenz” bar adjuster assembly. This assembly has a rack and pinion unit that adjusts the bar by turning a “screw” internal to the bar which pushes on the bar mount studs moving the bar forward or backward.

Avoid Injury by Getting Your Chainsaw Bar Assembly Right

Trying to use a chainsaw that is fitted with the incorrect bar (bar mount) is very dangerous and can cause physical injury. Always make sure the chainsaw you are using is fitted with the correct chainsaw bar!!!

It is possible to put the incorrect bar to a chainsaw, but it will not work or fit correctly. The bar can slip, come loose, the adjuster may not fit up correctly and most importantly the oiler will not provide proper lubrication for the chain.  Chain saw bars must match the correct bar mount for the saw in question.

In order for the saw’s oiler to properly provide oil to the chain the saw’s oil port has to line up with the bars oil holes. There is a small channel built in the bar mount pad of the chainsaw that directs the bar and chain oil. The oil hole of the bar lines up with this channel and allows the oil to flow to the saw chain. Proper lubrication of both the bar rails and saw chain is imperative to the optimum performance of the cutting system.

Figure 1 is an illustration showing three (3) different bar mounts. As you can plainly see they look very similar. But there are major differences. Notice the difference in width of the groove. Also notice the difference in the diameter of the adjuster pin holes above and below the groove. There are also differences in the placement and size of the chain oil pickup holes. All these differences make it plain that while the bar mounts are similar they are major differences.  Finally notice the difference in the radiuses and angles at the rear of the bar mount. While they are similar, there is enough difference to cause tracking and fit up problems for the saw chain. These radiuses control the tracking of the chain as it enters and exits the bar groove. There is also the fact that the chain is either .043, .050, .058 or .063 gauge and bar’s groove is sized to accommodate the correct gauge of saw chain.

Again it is possible to run a lower gauge chain in a bigger gauge bar, but this is not only a safety issue it will diminish the quality of the cut. For example, running .050 gauge chain in a .063 gauge bar will allow the chain to slip around in the bar and possibly even come out of the bar groove.

So it is important that steps be taken to insure that the chain saw bar is the correct bar for the chainsaw you are using. Discount Online Parts is a proud provider of Oregon Chainsaw bars, saw chain, sprockets, and accessories.

Figure 1.

Image courtesy Oregon Cutting Systems