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Re: My new alignment template generator

Posted: 03 Mar 2018 01:14
by Budddhacide
Hi all. Im trying to print an arc protractor for a fairly obscure tonearm (helius omega 10inch) using the conrad hoffman generator. The manual for the tonearm says the pivot to spindle distance is 236mm, and the overhang is 18mm. However, when i enter 236 into the generator its reporting the overhang as between (DIN ) 15.428 and (typical) 17.103. IEC is in the middle at 16.338. Trying for a lofgren A (baerwald). But none of the configurations im choosing have overhang at 18.

Any insight? Thanks.

Re: My new alignment template generator

Posted: 03 Mar 2018 03:53
by Sunwire
Ignore the 18mm overhang specification.
You are not using the same alignment as the original tonearm manufacturer.
This is NOT a problem.
But it is the thing most often confusing to new users of the template generator.
It mystified me for quite awhile.
Once I understood the geometry of the task better, I realized it didn't matter. Each alignment strategy will require a different overhang and offset angle. That's OK.

If you want a more complete explanation, you may find it by searching through previous posts in this thread, especially near the end of the thread.

Re: My new alignment template generator

Posted: 03 Mar 2018 05:44
by Budddhacide
Thanks! Much appreciated.

Re: My new alignment template generator

Posted: 03 Mar 2018 15:51
by tketcham
Hi, Budddhacide,

In the case of that Helius Omega 10, the intended(?) alignment geometry is a bit unusual; either that or there's a misprint in the manual. To get the geometry closest to the stated 18mm overhang you'd use Lofgren B and Hoffman's "Typical" groove radii, ending up with an overhang of 17.5mm and an inner null point at 73.9mm. Maybe the overhang spec in the manual was rounded up?

I forced an 18mm overhang using the Template Generator by using the Lofgren B alignment and setting the inner modulated groove radius at 64.5mm, which is getting close to a common Lofgren A inner null point of 66mm!

If you want to see a graphing of the alignments I'm talking about, use the Vinyl Engine "Tonearm Alignment Calculator Pro" tool and run the following:

Name: "Arm1"
Pivot to spindle: 236mm
Alignment: Lofgren B
Outer groove radius: Custom 145mm
Inner groove radius: Custom 63mm

Name: "Arm2"
Pivot to spindle: 236mm
Alignment: Custom
>Overhang: 18mm
>Offset angle: 22.31 Degrees
Outer Groove Radius: Custom 145mm
Inner groove radius: Custom 63mm

Given the atypical geometry of your Omega 10 headshell, if it can accommodate a Lofgren A cartridge alignment, that's what I'd start with, too. I like using the IEC groove radii but if the headshell won't handle the resulting 16.3mm overhang, the "Typical" groove radii ends up with a 17.1mm overhang.

Give those "Tonearm Alignment Calculator Pro" graphs a try and experiment with settings; they're very informative.

Regards,
Tom

Re: My new alignment template generator

Posted: 04 Mar 2018 01:23
by Budddhacide
Thanks Tom. I will have a look. Maybe you could take a look at this and see if I'm reading then specs right. There is actually an error on the same template. It says the hole for the pivot is 39-40mm. However, it turns out it's 43.5 confirmed by a few people and the manual.). I suppose this might affect things wouldn't it. Also, have I maybe confused the meaning of the numbers?

http://i67.tinypic.com/opppj4.jpg

http://i63.tinypic.com/6ofjlx.jpg

This sort of ambiguity is infuriating considering the price. The manual is filled with spelling errors etc...also. I'm not especially tech savvy. Im easily confused, lol.

Re: My new alignment template generator

Posted: 04 Mar 2018 22:01
by tketcham
I'm not able to read all of the instructions on the template sheet so I'm not sure what they're trying to say. The tonearm pivot is offset from the mounting post and looking at photos of the tonearm, it looks like it's difficult to determine the actual pivot point of the mounted tonearm so that complicates things.

Are you trying to install the tonearm or is it already installed?

Tom

Re: My new alignment template generator

Posted: 05 Mar 2018 00:23
by Budddhacide
I'm having a table made. I'll be adding the tonearm whenever it arrives. I bought the arm used, and there is nothing conventional about it. The designer refuses, for example, to provide an effective mass. He sent me to a physics heavy link beyond my comprehension arguing that it's irrelevant. Suffice to say straight answers are not forthcoming here.

Basically the template gives an effective length of 254mm, then another measurement of 236, which I assumed was the pivot to spindle distance, and then another 18mm, which I assume is the overhang. None of this is specified at all in the manual. So I'm not sure if ive even interpreting the numbers right. Does effective length =(pivot to spindle + overhang)?

Re: My new alignment template generator

Posted: 05 Mar 2018 00:27
by Sunwire
Yes, effective length =(pivot to spindle + overhang)

Re: My new alignment template generator

Posted: 05 Mar 2018 02:19
by tketcham
Budddhacide, are you having the turntable maker also construct a mounting board for the tonearm? Or is the tonearm going to be mounted directly to the 'table?

As long as they have the mounting template and use the specifications shown, you should be OK. It's a beautiful tonearm but esoteric products are inherently unconventional. :-)

Tom

Re: My new alignment template generator

Posted: 05 Mar 2018 23:52
by Budddhacide
Thanks Sunside.

Tom - yes, the retailer has gone to some trouble to make sure the armboard is correct. Andnthen I'll be stuck with it because nothing else will fit, lol.

Re: My new alignment template generator

Posted: 06 Mar 2018 04:55
by Conrad Hoffman
Not much to contribute, just following with interest. Their marketing info is sufficiently non-specific as to tell me nothing, and that's no doubt by design.

Re: My new alignment template generator

Posted: 06 Mar 2018 18:01
by Sunwire
Budddhacide, can you scan and upload the manual and mounting template that came with your arm and any other documents that came from the manufacturer?
There is no information about this arm in the database or library on vinylengine.
It might be useful to others and those on this thread who are trying to help you.
https://www.vinylengine.com/ve_uploads/ ... _scans.php

Re: My new alignment template generator

Posted: 08 Mar 2018 23:03
by Budddhacide
Yeah, I'd be happy to. Work has me moving around a bit but as soon as I'm able to get to the copier with a free moment ill get on it.

Conrad, thanks. I know it's a bit daft isn't it? I just hope it sounds good, lol

Re: My new alignment template generator

Posted: 12 May 2018 08:20
by scho2684
Conrad, maybe already covered somewhere:
Why do you have 2 grids on that protractor?

One is enough, put stylus tip on the radius (overhang is set correct now) and then align by twisting the cartridge on one grid...

Re: My new alignment template generator

Posted: 12 May 2018 17:17
by wolfie62
2 grids give absolute confirmation that the alignment is dead on. Keep the 2 grids!!