Sunday, September 26, 2010

#36- RAS-styles & alignment

Radial Arm Saws (RAS) are best known for being used to perform repetitive cutoffs on wider, or longer, boards. I have seen extension tables that would allow someone to lay up 30-foot boards and cut them shorter. This would be very hard to do on a table saw. A RAS can do that very easy because the head moves, not the actual workpiece.

Speaking of the head moving, there are two types of RAS’s. The first and most economical is the “regular style”. I call it that because I don’t believe there is an actual name for it. This RAS simply has an upright column at the rear and that has an arm attached to it that is sticking out from it towards the user. That arm has a grooved track built into it and the head’s roller bearings ride along those grooves to allow it to slide fore & aft. This saw is the one most seen in home shops and it is very fussy about aligning properly. At the outer end of the track, arm flex can be an issue.

The more professional design is the “turret-arm” RAS. The rear column is still there, as is the arm coming towards the user…but that arm is only ½ as long and it has a pivot point for the actual arm that has the track in it. The track arm- picture an upside down T, with the track being in the crossbar of the T and the stem being the pivot point- contains the grooves for the head’s roller bearings. This type RAS is far easier to align and has much less flex than the ‘regular’ design.

With a turret-arm RAS, achieving proper saw alignment is easier because having the track pivot in the middle allows the adjustment to better control the track arm. With the regular style, when the head is at the end closest to the user, there is always some flex. Maybe not much, but some…and the user has to factor that in when making their cuts.

Aligning a RAS is not all that complicated. I always suggest that the user get a piece of stock that is as wide as their saw can handle, lay it on the table, make a cutoff pass and check it with a framing square. Note: I don’t like using framing squares under normal conditions, but it’s about the only thing that has the capacity to check a wide-cutting RAS. Once the cutoff is checked, then the adjustments can be made. On a regular RAS, the alignment screws are located at the rear junction of the track arm and the column. On a turret-arm, the adjustment is made at the centered pivot point.

Follow your owner’s manual, check your adjustment results by making another cut off of the wide board and you’ll have your saw cutting straight in no time.

Send your questions or comments to:
Toolsmartz@bellsouth.net and we’ll see what we can do to help you.
_______________________________________________________________
Any views or opinions presented in this article are solely those of the author and do not necessarily represent those of this newspaper. Neither the author, nor this newspaper, accepts any liability for the content of this article, or for the consequences of any actions taken on the basis of the information provided.

#35 - RAS- choose the best blade

More of our on-going discussion about the Radial Arm Saw… Let’s see, where were we?... oh yes, we ended up talking about Positive and Negative blade hook angles.

My best description of how to check a sawblade’s hook angle was the ‘intersecting line method’ that I outlined last week. My second-most used visual to help understand this is that of a swimmer’s hand. If the hand is scooping the water, he is using a ‘positive hook angle’, but if the hand is laid back and just slapping water, it is a ‘negative hook angle’ effect. The swimmer won’t go anywhere using a ‘negative hook’ hand angle, but such is not the case with a spinning sawblade. It still cuts just fine when a negative hook angle is used, but because it is not digging or scooping, the operator has maximum control over the head and blade.

High-speed steel sawblades (those without carbide tips) are not really described in terms of ‘hook angles’ because a HSS blade truly cuts through the wood, whereas a carbide-tipped blade ‘scrapes’ its way thru.

Years ago, on any saw where the blade was suspended over the workpiece (ex: a miter saw; Delta’s “Sawbuck”, a sliding miter saw, or even a sliding compound miter saw) one would never see any blade on it, other than a negative hook. For some reason, that has changed. Now, one might see a 12 to 15degree positive hook blade installed on one of these saws, right out of the factory. While I am not going to speculate as to why the manufacturer’s decided that they could do this, I will say that I, personally, am not comfortable with it. As I told about in my example of testing, a negative hook blade offers the user so much more control over the sliding head, that to use any positive hook blade just invites ‘climb-cutting’.

On miter saws, where the head does not slide, a positive hook blade could be used and it still be as safe as using it in a table saw (which is another discussion entirely) because the head is ‘locked in’. There is no sliding movement as there is on a Radial Arm Saw or a sliding miter saw. With this in mind, I can understand it, but on a sliding miter saw? Not for me.

Hopefully, from our discussions, you have a better understanding of some of the techniques of a Radial Arm Saw’s blade needs. Next week, we’ll take a look at the different styles of RAS’s and get a tip or two about how to go about properly aligning a RAS

Send your questions or comments to:
Toolsmartz@bellsouth.net and we’ll see what we can do to help you.
_______________________________________________________________
Any views or opinions presented in this article are solely those of the author and do not necessarily represent those of this newspaper. Neither the author, nor this newspaper, accepts any liability for the content of this article, or for the consequences of any actions taken on the basis of the information provided.

#34- Radial Arm Saw- How’s your Hook?

Last week, we started a discussion about the Radial Arm Saw and I covered a couple of the reasons as to why I am a member of the ‘pull the blade through the workpiece’ camp. We’ll continue the discussion this week with reason #3.

Third, IF the proper negative-hook sawblade is used, the operator has complete control over the force of the blade thru the wood. Now, IF a positive-hook blade is used, the blade will try to ‘climb’ thru the workpiece and make the operator push back against it. ALWAYS use a negative-hook sawblade on your Radial Arm Saw.

I did some testing years ago and it really is true. Using the ‘pull-through’ method, with a 20 degree positive-hook blade, I had to push back against the saw head slightly to keep the blade from trying to ‘run’ towards me. On the other hand (again using the pull-through method), when I used a 15 degree negative-hook blade, I could use one finger to pull the blade thru the wood and it did not try to climb at all. In fact, I would let the head stop every couple of inches and just let it sit there…and it wouldn’t move, even though the blade was spinning at 3450rpm and buried in the wood.

This might be a good place for a talk about negative and positive blade “hook angles” because they do have an effect on how smoothly a RAS blade can pass thru a workpiece. For this discussion, we are talking about carbide tipped blades. Picture, if you will, a circle. On that circle, we draw a straight line vertically and a straight line horizontally - with the intersection of the two lines dead center in the middle of the blade’s hole. Now, we give that circle some blade teeth and let’s say that the ‘blade’ is going to rotate, and cut, counter-clockwise. Align one particular tooth right on the vertical line.

With that picture firmly in mind, here are your three ‘hook angle’ definitions:
If the flat of a tooth is exactly aligned with the vertical line, that blade is a ‘zero hook angle’ blade.
If the flat of the tooth has its upper tip tilted in the cutting direction (in our example, that would be counter-clockwise) this blade is a ’Positive hook angle’ blade.
If the flat of the tooth has its upper tip tilted AWAY from the cutting direction (in our example, that would be counter-clockwise) this blade is a ’Negative hook angle’ blade.

We’ll pick up here, next week.

Send your questions or comments to:
Toolsmartz@bellsouth.net and we’ll see what we can do to help you.
_______________________________________________________________
Any views or opinions presented in this article are solely those of the author and do not necessarily represent those of this newspaper. Neither the author, nor this newspaper, accepts any liability for the content of this article, or for the consequences of any actions taken on the basis of the information provided.

#33- The mysterious Radial Arm Saw

OK, let’s get back to the task of learning more about our many shop tools and machines. This week, we’ll take a look at one of the most versatile machines, but also one of the most dangerous.
The Radial Arm Saw. Sometimes, the very words can make a grizzled woodworking veteran recheck his hands to make sure he still has all of his fingers and thumbs. This machine requires THAT much caution when using it.
But, as with most machines, if you respect it and realize what it can do to you in a heartbeat… you simply must be careful.

Just so that we are all on the same page, let’s outline a few parts of the saw.
The “head” is the part of the saw that holds the “sawblade” and slides fore and aft on the “track”. The “track” is the “arm” of the saw that holds the “head”, which is sometimes also called the “carriage”. The “fence” is the barrier that the workpiece is held against while laying on the “table” which references the workpiece, prior to being cut. The “off” position of the head/blade is when the head is fully retracted towards the rear of the saw, behind the fence.

Alright, now let’s take a look at one of the more frequent questions that I’ve been asked: “Should I pull the blade thru the wood, or push it through?” While I am sure that I may get some pushback, I will state my case and the reasons that I believe as I do. In my opinion, the blade should be pulled thru the workpiece. Here’s why.

First, when the blade and head are at rest, they are retracted behind the fence, away from the operator. That is a good position to then start the saw up, without it being hung out in space next to the operator.

Second, the proper blade rotation is over the top towards the operator, and down and under and away from the operator. Given this, if the head is retracted behind the fence and turned on, then pulled into the wood, the first contact the blade has with the stock will be pushing the stock down into the table and towards the fence. That places all of the cutting force downward towards the table, and rearwards towards the fence – both are very good things because they properly brace the workpiece.
If the blade were to be pushed into the stock, the first blade contact would tend to lift the workpiece…NOT good.

Next week, we’ll tell you more about the Radial Arm Saw.

Send your questions or comments to:
Toolsmartz@bellsouth.net and we’ll see what we can do to help you.
_______________________________________________________________
Any views or opinions presented in this article are solely those of the author and do not necessarily represent those of this newspaper. Neither the author, nor this newspaper, accepts any liability for the content of this article, or for the consequences of any actions taken on the basis of the information provided.

#32 - Reviving The Dead Hot Rod - part 3

Picking up from last week… the little ’34 Ford coupe is painted and suffering from a worn out coil. Run it until it gets warm and it’ll stop working until it cools off. We finally decided to make a homemade adaptor to be able to use a new coil (we didn’t even know enough to realize that somebody, somewhere probably made new ones). So, the car runs and I go into the Navy for a few years. For some reason, dad just never again had any desire to drive the coupe around- so every time I’d come home on leave, I’d charge the battery, drive her around a bit and then park it until next time.

In 1996, dad finally decided to put hydraulic brakes on it. He found a good deal on some parts in Halls, TN that would make the job fairly easy…and guess who got commissioned to do the work? His one and only son, me.

Well, we changed the front end, the rearend, ran hydraulic lines and fabricated a mount for the master cylinder. It did stop better after that.
But after that spurt, she went right back into the garage. It’s really amazing what damage a car can suffer just simply sitting in a garage. Things fall over on it, stuff gets spilled on the fenders and dust grows by the pound. It sounds bad, but it really gave the little car some ‘character’…like it had been used all those years. It’s a secret that only we know.

Well, time does pass and one day in 2001, I was visiting dad and he asked me for a dollar. Sure I asked for what, but he hounded me until I gave him one and he handed me the title to the coupe. Wow. Now I had my own real Hot Rod.

Since then I have tried to make the car as safe as possible and look like it was built in the 50’s. I changed the electric system to 12 volt, split the front wishbone, added tube shocks, put in safety belts, changed to late model wire wheels and radial tires, revived a 2 carb intake that dad used to run on his dirt track race car in the late 50’s, got a new radiator and electric fan and installed a set of finned aluminum heads. Without the hood is my chosen method of running it, and it really looks like it would do a hundred miles an hour.

Keep an eye out for us around the ‘boro and if you see us, honk & wave. We spend a lot of time at our AACA club’s garage down in Cannonsburgh.

Monday, September 6, 2010

#31- Reviving The Dead Hot Rod - part 2

Picking up from last week… the little ’34 Ford coupe is sitting in our backyard in Memphis, and has been for 9 years. It was my junior year in high school and the 1st Street Rod Nationals, for cars built in 1948 or earlier, had been held in Peoria, IL in 1970. I read all about it Rod & Custom magazine, but of course, I wasn’t there…Well, lo & behold, in 1971 the 2nd Street Rod Nationals came to the bluff city. I drove down to Highland Ave at night and all those Hot Rods and beautiful cars in the street lights was a sight to see. I was in ‘car nut’ heaven!

So, I’m hanging out checking out all those hot rods and thinking “Wow, I wish I had a car like these…HOLD IT!...There’s one of them in our back yard!!!” So, over the next few weeks, I talked my dad into footing the bills and me doing the labor to fix up the old ’34 and he agreed.

The first thing we did was get the car ready for the engine and believe it or not, when we went to my dad’s friend’s garage, the fresh 1936 motor was still there in it’s plastic bag. We towed the car up there and used his engine hoist to put the motor back in the car. Over the next few weeks, we got the motor running - fall of 1971.

That turned out to be the easy part. Mechanically, I am a wiz, but I found out real quick that body work is not my strong suit. I just don’t have the ‘touch’. I can lay down paint with the best of them, but don’t ask me to smooth out a body panel…even now, when people see the car, I tell them “If the body work looks like a 16 year old kid did it…it was me”. Over the course of the next 2 years, I disassembled the car, right down to the point of removing the body from the frame. We didn’t do that because we had no garage to store it in. But we had the fenders off and sanded everything down to bare metal so that we could put lacquer paint back on it.

By the summer of 1973, we had painted the car black & yellow and we had figured out that the distributor coil was bad. It would run fine until the coil got hot and then it would leave you stranded until it cooled down.

Next week, we’ll finish up the story of the Hot Rod.

#30- The Hot Rod Detour- part 1

I think we’ll take a ‘detour’ this week and let you know more about my other passion - aside from the care and feeding of woodworking machines and Taylor-Tot strollers. I love Hot Rods - Ol’ Skool, fire-breathing Hot Rods.

You might recognize those words from column #13, but they sounded so good, I decided to use them again and let you know a bit more about our 1934 Ford coupe’. In the mid 1950’s my dad was a Memphis/Mid-South area truck driver who delivered auto parts to those mom ‘n pop parts stores (that have almost faded away, thanks to AutoZone, Advance, etc…) and he was actively seeking a decent 1934 car because it was the year he was born in.

Well, on one of his trips, he wound up in Greenville, MS and ran across a nice little ’34 Ford. The kid that had it had hit the back end of another car and his mom was making him sell his car…for $100. That was quite a bit of money back in 1958, but dad scraped it together and bought the car in November.

He brought it home and proceeded to use it for driving back and forth to work. At that time he had to get up around 4am and I remember my mom getting up many a morning to push him down the street, so the ’34 would start. Around 1962, the motor’s block cracked and needed to be replaced. Dad pulled the engine out and during one of his runs to Blytheville, Arkansas, he found a freshly rebuilt 1936 short block for $50. (yes, ½ the price he paid for the whole car) The ’36 motor is better because it has insert bearings. The original ’34 motor uses babbited bearings, which is much harder to repair, if need be.

Anyway, he purchased the rebuilt block and brought it home, but since we didn’t have a garage at the time, he took it to a friend who lived in the next block and stored it in his garage.

Well, time moves along and one thing led to another and after 9 years, that motor still sat in his friend’s garage, and the ’34 still sat in our backyard without a motor. Yes, I had gotten in trouble a few times for ’playing’ on it, and there is no telling how many people stopped by our house to see about buying the little coupe...no matter how hard we tried to hide it from view of the road. Dad never sold it. Next week, I’ll tell you how it came back from the dead…’til then.