Before we get into the meat of this article, let me say thanks to all the fine folks who sent pictures of their shop pets in machine shops around the world. There are some good-looking shop pets out there.
Let Me Level With You!
Are we on the level? Are you half a bubble off? I know I have been told that many times. Why am I asking these questions? And what do they have to do with machine maintenance? I’m asking because your level needs to be leveled or calibrated before you can do any level of quality work!
This article will focus on the seat and guide machine, as this it is one of the most misunderstood leveling processes in the shop.
Does this ever happen in your shop? You install a valve guide but when you grind or cut the seat, the main angle is fat on one side and skinny on the other? This is your telltale sign that your level is not calibrated properly.
Ready? Set? LEVEL!
First let’s inspect our level. Look closely at the vial to see if there are any cracks. Also check the size of the bubble. If it’s larger than the viewing glass, replace it. Levels are filled with alcohol and if a crack is present on the vial it will evaporate making the bubble larger and larger until it is gone.
If your level is designed to fit over the top of the pilot, then check the inside diameter to confirm that it’s not worn. If you have a .375? pilot, the ID should be no larger than .376?. This spec should be the same for all pilot sizes.
This is also a good time to measure all the tops of your pilots for wear. Again the spec is .001? to .0015? and then it’s time to replace.
Remember to allow no more than .001? of wear to occur before replacement. Some seat and guide machines levels have a V-type groove to accept most common pilot top sizes. Ensure the groove is not worn. Inspect the adjustment screws and lock down nuts. Make sure they adjust easily and the nuts lock down. Inspect the thumbscrew to confirm it rotates smoothly and has a locking setscrew to secure the setting.
Next, let’s chuck our level into the drill chuck that came with your machine. Now position the level in front of you going left to right. Take a reading, and then rotate the level 180-degrees. Now take another reading. Do the readings match? Probably not.
Why? It was level in the front, why isn’t it level in the back? Because the level is not level. The level will come out of calibration with regular use. It will get bumped against the machine or cylinder heads, and sometimes will even fall onto the workbench. I recommend strongly that you try to protect your level from these kinds of impacts. This is a precision measuring instrument and should be treated with care.
Here is how we fix it. Say the level was off one line to the left when rotated to the back, and when you rotate it back to the front it is level again. Loosen up the setscrew of the level and make an adjustment of half of one line. Lock down the setscrew. You might say well now it is off in the front too! Yes, this is true, as we have yet to level the level.
Rotate the level back to the back again. Did it repeat? If it did then you got it right on the first adjustment. However, in most cases you will need to repeat this until the level repeats itself at each position. Even if the bubble is still not in the middle as long as it repeats in both directions…you have achieved level of the level…got it? If not go through this procedure again.
Now, open your toolbox and get the correct socket and adjust the machine leveling screws to bring the level bubble perfectly between the lines. Make sure you have leveling pads underneath the leveling screws. We don’t want to have screws drilling themselves into the concrete. Be sure to level front to back and left to right.
Rotate the level to the back and take a reading. The bubble should be exactly in the same place as it was in the front. Rotate the level 360-degrees all the way around. If you have performed this procedure correctly the bubble will not move and will stay perfectly between the lines during the entire 360-degree rotation.
If not go thorough the procedure until that bubble stays put for the full 360-degree rotation. Ok, now rotate the level to the left and take a reading. Rotate the level to the right and take a reading. Is it the same? It should be. If not, start over again!
You can now put a cylinder head in the machine. Insert the correct pilot, and put the level on the pilot. Now you can level the cylinder head, front to back and left to right. Remember if the level gets bumped, all you have to do is re-do this procedure and your level will be level, your cylinder head will be level. And guess what? Your valve guides will go in straight and be more concentric to the ID of the valve seat.
One other note: Not all non-concentric valve guide installation is the fault of the level. We’ve found some valve guides are not concentric right from the manufacturer. Even if you have a perfectly calibrated level if you install one of these less than ideal guides, no amount of grinding is going to bring the seat to concentricity.
Okay, now let’s check the level of our surfacing machines. But first we need to again make sure the level is level.
For most machines you will do a two-point level. I recommend using a 12? Starret level that you are sure is calibrated properly. To see if your level is accurate simply place it on a surface you know is flat and take a reading. Then reverse your level 180 degrees. The reading should repeat. Even if the bubble isn’t directly in the middle, as long as the reading repeats you know that the level is accurate.
If it doesn’t repeat, do a quick calibration. Take a reading to determine how far the level is off. Now adjust the level, splitting half the difference that it’s off. Again set the level back down on a surface, turn it 180 degrees and keep adjusting until it repeats. Now you’re on the level!
Set your level on the ways of your machine or on the mounting surface of the table. Adjust the machine front to back as well as left to right. When you’re done, all surfaces should read level in all directions and the bubble should stay in the middle.
Let’s Get Down To Specifics
Okay, enough theory; let’s get down to work. Here’s how to level a broach type of surfacing machine such as the 530/570 Van Norman and 850 Storm Vulcan Stormill.
The broach is probably the easiest machine to set up in any shop. These types of machines have been around a very long time, and even though they are no longer manufactured there are still quite a few of them in operation today. These machines are also the hardest to get level and the hardest to stay level. Why? It is because they require a 4-point level.
What is a 4-point level? Well, I am glad you asked. A four-point level for broaches includes leveling off the lower carriage ways. These ways actually carry the table when cutting. Not using these as leveling points will cause a back-cut or twist in your machine and cause an undesirable finish to the work piece.
First, we need to have an accurate and calibrated level to start (you knew that was coming, didn’t you?). If your level isn’t level go through the previous procedure and ensure your level is calibrated prior to starting this leveling exercise.
Next, make sure your leveling bolts have metal leveling pads for the bolts to nest in, these are generally about 4-inches square with a divot in the middle for the leveling screw. Always use leveling pads and never let the leveling screws, screw themselves into the concrete.
Now, take a reading on the front way of the broach. Set your level so it’s straight and running left to right in front of you, and then take a reading on the back way placed in the same manner as in the front. If you see a difference in these two reading you have a twist in your machine.
Another indicator for twist is to listen very closely to the machine when it is nears the end of the cut. If you hear a dragging sound or a “back-cut” this sound is telling you that your machine has a twist in it. You can also look closely at the freshly machined surface. If you see a crosshatch pattern on the surface it also means you have twist in your machine. That is why we need to do a four-point level for this type of machine design.
Okay, you’ve checked the front and back ways and found the machine is out of level left to right. Go ahead and adjust the leveling bolts to bring the machine level left to right. Now, we need to place the level across the ways. This can be a challenge as the distance from these ways in generally more than the length of even a 12? level. I have found that using a precision ground piece of metal that is long enough to reach both ways, works very well for this part of the leveling procedure. Take a reading on the left side and note the reading, now take a reading on the right side and compare these two reading.
It is very important that when you make the adjustment that you affect small amounts of adjustment to achieve level. Attempting to make the full correction will be like chasing your tail. I always do the left and right first on the front, then left and right on the back. Then go and adjust the front to back on the left and then adjust the front to back on the right. When you are done you should be able to place your level on any of those four points and read level.
Remember just because you have leveled your machines now, does not mean they will stay level. The normal course of business will create enough vibration to effect level. Traffic from the street, your own forklift, people, and just the general activity of your shop will affect level. Keep up on it by adding this check to your weekly or monthly maintenance for your entire shop.
Remember, I am on the level with you, so be on the level with all of your machines in your shop.
See ya in the shop!