Are tolerances tight for tensions arms?

[cjacek]

Another potential trivial question but here goes .......

Are the tape tensions arms, as found on the extreme left and right side of the typical open reel machine (38, 48, TSR-8 etc), supposed to be dead straight, have the same tight tolerance, for example, as heads do or can they be off a bit here or there? A "bit" meaning, approx a mil or two or thereabout from dead center.

Thanks.

 

[The Ghost of FM]

I can't see a need for them to be as perfectly aligned as the heads in that their main function is to contribute to providing consistent tension more then anything else though they should be reasonably straight vertically to facilitate neater packing of the tape on the reels. Most of them don't provide all the angular adjustments that heads are equipped with and rely on themselves not being bent out of position from accidents of impact that might bend the metal out of its factory trueness.

Do you have a bent tension arm, Daniel?

Cheers!

 

[cjacek]

Thanks for the reply Jeff.

Well, I don't know if the 2 arms are slightly off or I'm being anal again or what..... but tell you what, I'll post a couple of picts and you'll decide if they're fine or not.

Let's see, where's my camera at.....

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[cjacek]

Jeff, here are some random photos (I don't want to influence you but the left arm especially looks a bit off):

 

[cjacek]

Continued.......

 

[A Reel Person]

I'd say it's bent, very slightly. You'd probably be okay to bend it back slightly.

An unwanted effect of a roller that's not in parallel to the tape path & other rollers would be to put uneven tension on the tape, which could possibly stretch or skew the tape in an uneven fashion across the width of the tape. That type of tape wear problem in the extreme case would probably cause noticeable flutter and phase problems between the left and the right tracks.

 

[cjacek]

Dave, you mean the left one? That's what I thought. It's like someone pulled up on it when lifting the machine or something .... I dunno .... Anyway, when you said bend it back, how exactly (and with what) do I do that?

 

[A Reel Person]

Rule of thumb: Do it gently if at all.

The 7th picture in the sequence seems to be at an oblique enough angle to make it look off kilter. Yes, the left one.

Spec: You've determined with the naked eye that something's out of alignment, so you use the same technique to bring it back into alignment. You eyeball it.

Good luck.

 

[cjacek]

OK, I get what you're saying but in actual mechanics of doing it, do I just g e n t l y (of course), pull on it, the roller, with my hand? No need to remove anything or use any other tools? Just gentle pressure, with my hand, to bend it back?

 

[cjacek]

SUCCESS!!!

Dave, I just did the above and it seemed to have helped! What a relief I don't have to dismount anything! Amazingly it didn't take much manual pressure to bend it back into a more uniform place. I can now see how easy it is to bend those tension arms. In your estimate, what is the actual structure in there that is the weak link and enables it to bend like that?

Thanks again Dave.

 

[The Ghost of FM]

If it didn't take much pressure to bend it back from its outward stance with no tape loaded on the deck, consider the possibility that a loaded reel of tape on the machine may have done the same job and that there was no alignment issue in the first place! ...Perhaps they engineered the metal to be semi-ply-able to facilitate slightly out of true reel tables?

Were you getting decently neat tape packs under the spooling mode prior?

Cheers!

 

[funkytonk]

Hey those are really nice, clear photos, what type of camera did you use? Is it just me or in that one photo do you still have christmas decorations up?

 

[cjacek]

If it didn't take much pressure to bend it back from its outward stance with no tape loaded on the deck, consider the possibility that a loaded reel of tape on the machine may have done the same job and that there was no alignment issue in the first place! ...Perhaps they engineered the metal to be semi-ply-able to facilitate slightly out of true reel tables?

Were you getting decently neat tape packs under the spooling mode prior?

Cheers!

Jeff, good point about these possibly being purposely engineered to be slightly off but, on the other hand, I would expect that both arms would be 'off' and not just the left, which was significantly worse that the other, kind of tilted up toward the reels. Plus, non of my other [albeit 1/4"] decks have this issue. Another thing is that when I tried to thread the tape, I noticed that when going under the tension arm and then up over the roller, that the tape seemed to be skewed somewhat, like one side [closer to the deck] was touching the tension arm roller more than the other. I knew it shouldn't be like that. What do you think? Thanks.

 

[cjacek]

Hey those are really nice, clear photos, what type of camera did you use? Is it just me or in that one photo do you still have christmas decorations up?

Thanks for the kind comments. The camera used [wait for the drum roll]....... is........ a 1 mega pixel Sony DSC-P30! Yup, it's quite an oldie, made several years ago but I wouldn't upgrade it either. It has a nice macro setting as well as a manual over-ride mode and pretty cool night shot feature [which I used on those BTW with no flash]. I will tell you though, that it's technique rather than the camera [as with audio recording]. I've used this P30 for about 6 years and always figure out a way to get better picts. To give an example, I used the night mode on this, set the camera on something solid so that it wouldn't vibrate [also used a timer] and played around with focus (sometimes focusing on my hand where I wanted it sharp) and also the amount of light ........

......and yes, that indeed is a Christmas tree!

 

[funkytonk]

Jeff, good point about these possibly being purposely engineered to be slightly off but, on the other hand, I would expect that both arms would be 'off' and not just the left, which was significantly worse that the other, kind of tilted up toward the reels. Plus, non of my other [albeit 1/4"] decks have this issue. Another thing is that when I tried to thread the tape, I noticed that when going under the tension arm and then up over the roller, that the tape seemed to be skewed somewhat, like one side [closer to the deck] was touching the tension arm roller more than the other. I knew it shouldn't be like that. What do you think? Thanks.

I have two 48's and both tension arm rollers have a slight tilt towards the reel on both machines. The amount of tilt isn't consistent either. I think it just might be one of the 'other' weak points of the deck.

It seems like the spindle of that roller is riveted to the tension arm. So that makes me a little nervous about straightening out those rollers. I think they are supposed to be "dead straight" but I don't want to wear out that rivet joint.

I think I know what you are talking about with the tape being skewed on the tension arm roller. It is just on the take up side right? Right after the tape leaves contact with the roller heading up towards the take up reel? Both of my machines do the same thing. The one that is skewed the worst has a more severe tilt of the tension arm roller. So in theory straightening the roller should take out some of that skew.

 

[The Ghost of FM]

Jeff, good point about these possibly being purposely engineered to be slightly off but, on the other hand, I would expect that both arms would be 'off' and not just the left, which was significantly worse that the other, kind of tilted up toward the reels. Plus, non of my other [albeit 1/4"] decks have this issue. Another thing is that when I tried to thread the tape, I noticed that when going under the tension arm and then up over the roller, that the tape seemed to be skewed somewhat, like one side [closer to the deck] was touching the tension arm roller more than the other. I knew it shouldn't be like that. What do you think? Thanks.

Well, back tension is usually set stronger then take up tension because the front end is being aided by the capstan and pinch roller and only dealing with the difference in load after that and onto the take up reel. Back tension is the sole job of the supply reel motor and should put more strain on the left tension arm.

But yeah, perhaps yours are/were off a bit...after looking pretty closely at the ones on my 38 and MS-16, which are both exhibiting pretty dead straight geometry, I guess yours may have been abused at some point in their past?

But, if you did manage to straighten them now, I guess we still have a happy ending!

Cheers!

 

[cjacek]

I have two 48's and both tension arm rollers have a slight tilt towards the reel on both machines. The amount of tilt isn't consistent either. I think it just might be one of the 'other' weak points of the deck.

That's very interesting indeed and strange that my machine and your 2 (also 48's) have that same issue. I think that you may be right with these being as the 'weak' points of the deck or it's one hell of a coincidence.

It seems like the spindle of that roller is riveted to the tension arm. So that makes me a little nervous about straightening out those rollers. I think they are supposed to be "dead straight" but I don't want to wear out that rivet joint.

I think that if you just steady and support the lower part of the roller while slightly pulling (bending) on the upper part, with that same hand / fingers, that it should be OK. I mean, when I did it, I really tried to be very, very careful. I think those things are built sufficiently well to withstand 'some' adjustment like this. I also think they should be dead straight.

I think I know what you are talking about with the tape being skewed on the tension arm roller. It is just on the take up side right? Right after the tape leaves contact with the roller heading up towards the take up reel? Both of my machines do the same thing. The one that is skewed the worst has a more severe tilt of the tension arm roller. So in theory straightening the roller should take out some of that skew.

The problem [was] with the left side mostly, as the tape leaves the reel and goes under and over the left tension arm. The tape was def not straight. The tension roller was not straight. [See especially the next to last photo - #7]. The right side is a lot better [although not perfect] and so is the tension roller arm. Yes, I'd say if you straighten those out, it'll solve the problem.

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[cjacek]

Well, back tension is usually set stronger then take up tension because the front end is being aided by the capstan and pinch roller and only dealing with the difference in load after that and onto the take up reel. Back tension is the sole job of the supply reel motor and should put more strain on the left tension arm.

But yeah, perhaps yours are/were off a bit...after looking pretty closely at the ones on my 38 and MS-16, which are both exhibiting pretty dead straight geometry, I guess yours may have been abused at some point in their past?

But, if you did manage to straighten them now, I guess we still have a happy ending!

Cheers!

Hey, thanks for [closely] looking at your 38 / MS-16 tension arms, Jeff. I don't know what relationship the back tension is vs why the left tension arm is bent, other than perhaps a weakness in the tension arm itself and / or possibly too much back tension compounding the problem but I think I'd agree, as you point out, that perhaps these were indeed 'abused' in their past life, like someone trying to lift the machine by them. I hope not!

In any case, I did manage to restore the geometry [to some degree of 'straight'] and thus we should have a happy ending indeed.

I hope I don't find any other gremlins in that 48, as I put it through its paces...

Currently awaiting shipment of a nice 6 screw take up reel..

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