Incra Miter V120 review of sorts (spoiler alert)

[reible]

While the V120 has been around for a while it is new to me. I expect it might be something other will be adding too.

If you like to figure things out yourself then let this be a spoiler alert, I will be covering a few things and showing pictures of the unit. Also keep in mind I will not be attempting to show things that are already covered pretty well in the manual.

I emptied the box and the contents are shown.

[ATTACH]21754[/ATTACH]

At this point I was more interested in the fit of the miter bar that I went to check that out before doing anything else. We had discovered that on the I-Box the miter bar was not countersunk for the adjustable white disks thus not being able to expand for a good fit (at some of had this problem). See this post for additional information:

https://forum.shopsmith.com/viewtopic.php?t=12807

I attempted to get a nice sliding fit but it wasn't even close to being a snug fit.

[ATTACH]21755[/ATTACH]

I removed the white disks and again there is no countersink on the holes.

[ATTACH]21756[/ATTACH]

In this case there are 4 holes that need attention. See locations, green tape is marking them. (The compass head needs to rotate to locate them all.)

[ATTACH]21757[/ATTACH]

Again a small countersinking allows the adjustment that I was looking for.

More to come.

Ed

[reible]

What I wanted to look at next was to see how square the face is to the bar. As you can see it isn't bad but is also not right.

[ATTACH]21758[/ATTACH]

Shimming is done to fix the issue. In my case the shim needs to be behind the mounting screws, had the angle been the other way then the shims would have to be before the screws. This picture show the second shim being put in, the other side already has the shim installed.

[ATTACH]21759[/ATTACH]

The first attempt was with some heavy paper, it measured .009", and that was too much as can be seen by the angle having gone the other way.

[ATTACH]21760[/ATTACH]

Found some thinner paper, .002" and that was just right, and the picture shows it.

[ATTACH]21761[/ATTACH]

Just a little more coming up.

Ed

[reible]

So far so good. The last task is getting the head square to the blade when set to 0 degrees on the scale.

I was using a rafter square and started by checking where thing stood after my other messing around. It looked pretty good but when I looked at where the square was touching the V120 I could see it was in the curved region.

[ATTACH]21762[/ATTACH]

By putting a 1/4" piece of MDF under the square it was now riding up on the face and yes I could see it was very close but not perfect. Seeing that allowed me to get that extra tweak so it is really square now.

[ATTACH]21763[/ATTACH]

That is as far as I got today, we will have to see what tomorrow brings.

Ed

[dusty]

Once again I am confused.

Is the hole that seems to need to be countersunk but is not the hole that receives the split nylon locking washers?

I have two Incra miter bars. One is countersunk and the other is not. However, they are both adjustable and can be adjusted to eliminate the slop in the miter bar.

The screws that secure the nylon washers to the miter bar (in the counter bores) are all the same.

The two sets of nylon washers appear to be interchangeable as well. One set is different in color (maybe a different material) but are the same form, fit.

Is what is the problem? I appear to not have one but I feel a need to better understand this issue because I might have a problem and don't recognize it.

My real question is this. What does countersinking the bar accomplish? It is reported here that the bar is loose. I assume that means the nylon locking washers cannot be secured in the position that is required to take the slop out of the miter bar.

If that is correct, why? The nylon locking washers are thick enough so that none of the screw, other than the threads, protrudes through the nylon locking washer so why is the countersink needed?


Question: On those miter bars that need to be countersunk, do the nylon locking washers spin out of position easily even when the mounting screws are tight? This would indicate to me that the screws bottom out too soon and the countersink simply allows the screws to penetrate a wee bit further.

If this is the case, I would conclude that a stacking of tolerances is really what causes the problem and why some versions of the miter bar can be secured when others cannot.

BECAREFUL: I split one of my nylon locking washers while playing with this. I am going to add the washers and mounting screws to my spare parts kit.

[dusty]

So far so good. The last task is getting the head square to the blade when set to 0 degrees on the scale.

I was using a rafter square and started by checking where thing stood after my other messing around. It looked pretty good but when I looked at where the square was touching the V120 I could see it was in the curved region.

[ATTACH]21762[/ATTACH]

By putting a 1/4" piece of MDF under the square it was now riding up on the face and yes I could see it was very close but not perfect. Seeing that allowed me to get that extra tweak so it is really square now.
[ATTACH]21763[/ATTACH]

That is as far as I got today, we will have to see what tomorrow brings.

Ed

Ed Reible: The aluminum plate that the square appears to be referenced on, is that a Master Plate? If it is, does it perform as a reference better than does a saw blade?

[fredsheldon]

Once again I am confused.

Is the hole that seems to need to be countersunk but is not the hole that receives the split nylon locking washers?

I have two Incra miter bars. One is countersunk and the other is not. However, they are both adjustable and can be adjusted to eliminate the slop in the miter bar.

The screws that secure the nylon washers to the miter bar (in the counter bores) are all the same.

The two sets of nylon washers appear to be interchangeable as well. One set is different in color (maybe a different material) but are the same form, fit.

Is what is the problem? I appear to not have one but I feel a need to better understand this issue because I might have a problem and don't recognize it.

My real question is this. What does countersinking the bar accomplish? It is reported here that the bar is loose. I assume that means the nylon locking washers cannot be secured in the position that is required to take the slop out of the miter bar.

If that is correct, why? The nylon locking washers are thick enough so that none of the screw, other than the threads, protrudes through the nylon locking washer so why is the countersink needed?


Question: On those miter bars that need to be countersunk, do the nylon locking washers spin out of position easily even when the mounting screws are tight? This would indicate to me that the screws bottom out too soon and the countersink simply allows the screws to penetrate a wee bit further.

If this is the case, I would conclude that a stacking of tolerances is really what causes the problem and why some versions of the miter bar can be secured when others cannot.

BECAREFUL: I split one of my nylon locking washers while playing with this. I am going to add the washers and mounting screws to my spare parts kit.

The locking plastic washer is split on one side so that it can expand. The inside bore is also tapered. If the tapered screw can't be tightened beyond it's current limits then the split washer can't expand enough to kiss the inside of the miter slot. That's my issue and it was fixed by allowing the taper of the screw to seat deeper into the miter bar than before by creating a deeper taper seat for the screw to mate up with. Did I make myself clear:)

[dusty]

The locking plastic washer is split on one side so that it can expand. The inside bore is also tapered. If the tapered screw can't be tightened beyond it's current limits then the split washer can't expand enough to kiss the inside of the miter slot. That's my issue and it was fixed by allowing the taper of the screw to seat deeper into the miter bar than before by creating a deeper taper seat for the screw to mate up with. Did I make myself clear:)

Yes, your position is quite clear but the question is why do your screws bottom before the split washer has adequately expanded? Apparently, the taper on the screw head protrudes clear through the split washer and bottoms on the miter bar.

When I put a screw in the split washer and view from the bottom, I see nothing but thread on the screw; about 1 1/2 to 2 threads.

Thought: the counter sink in the nylon washer could be different.

[fredsheldon]

[quote="dusty"]Yes, your position is quite clear but the question is why do your screws bottom before the split washer has adequately expanded? Apparently, the taper on the screw head protrudes clear through the split washer and bottoms on the miter bar.

When I put a screw in the split washer and view from the bottom, I see nothing but thread on the screw]

Dusty,

You might be on to something. I think the countersink in the washer is too deep and wide or the tapered screw head needs to be wider.

Fred

[reible]

Hi,

I took a couple of pictures and got a small sample of data to show.

Keep in mind if you can achieve the fit you want then you do not have to make any changes.

I've already modified my bar so I had to adjust what I did by using the same hole but on the other side of the bar. This side has no countersink. When I screw the screw in it bottoms out, at that point I measured the height of the head above the bar.

[ATTACH]21766[/ATTACH]

The reading was .135".

[ATTACH]21767[/ATTACH]

I then went to the other side of the bar where I had done the countersinking.

[ATTACH]21768[/ATTACH]

The measurement now reads .107.

[ATTACH]21769[/ATTACH]

Now this is my unique set of parts so you may not have the same measurements, especially on the countersunk side but it does show that the screw head can go lower then before and this expands the white plastic farther then before.

Again if you already have the fit you desire then you do not need to do anything. If you find like I did that I could not get a proper fit then either think about doing the countersinking operation or contact Incra directly to discuss your particular take on things.

Ed

[dusty]

Dusty,

You might be on to something. I think the countersink in the washer is too deep and wide or the tapered screw head needs to be wider.

Fred

The screw is standard and in manufacturing you do not want anything other than standard if at all possible. "Special" = "more costly".

This discussion is interesting and shows evidence that we (the user) does not know all that is needed to understand "why" things are the way they are. I have two miter bars (as stated earlier). One is countersunk and the other is not. Incra has made a change, subtle as it may be, that has brought this to be. We'll probably never know why.

The next time I talk to Mark, if I remember, I'll ask.