VintageBigBlue.org

 

Re: Pier mounting a G11


May 19, 2002

 


----------------------------

#10238 May 19, 2002

Hi all,



I'm new here and I am just coming from the LX200 camp. I am currently

putting in a new (first) observatory and decided to switch back to GEM

instead of the darn forks I've been fighting with for years. So after

looking for a GEM to use, looks like the G11 is going to be it. Now

for the question, can someone tell me the inside diameter of the top

of the upper tripod where the head fits into it? I am pricing a pier

from LeSeur

but, like anyone else, I'm trying to find out if I can do the pier any

cheaper myself,successfully that is! Thanks for all the good info on

this group, I feel somewhat familiar with the mount already.



Thanks,

Glen



----------------------------

#10244 May 19, 2002

let us know what you find out.. the way I look at it is that it should

not cost much to have a large pipe turned to the proper inside

diameter at a machine shop.



"madmaxxx47362" dernedid@...> wrote:

>I am pricing a pier

>from LeSeur

>but, like anyone else, I'm trying to find out if I can do the pier any

>cheaper myself,successfully that is! Thanks for all the good info on

>this group, I feel somewhat familiar with the mount already.



Herm

Astropics home.att.net/~hermperez



----------------------------

#10250 May 19, 2002

In a message dated 5/19/02 10:57:57 AM Central Daylight Time,

dernedid@... writes:



> I'm new here and I am just coming from the LX200 camp. I am currently

> putting in a new (first) observatory and decided to switch back to GEM

> instead of the darn forks I've been fighting with for years. So after

> looking for a GEM to use, looks like the G11 is going to be it. Now

> for the question, can someone tell me the inside diameter of the top

> of the upper tripod where the head fits into it? I am pricing a pier

> from LeSeur

> but, like anyone else, I'm trying to find out if I can do the pier any

> cheaper myself,successfully that is! Thanks for all the good info on

> this group, I feel somewhat familiar with the mount already.

>

> Thanks,

> Glen

>



Glen,

The I.D. of the tripod is 5.530 inches. I had a tripod made that I designed

rather than pay the "high" prices that LeSeur charges. My cost of

fabrication and material was $75 for the pier. The pier weighs 130 pounds so

getting it shipped to me was another $50. It was primered black when I got

it but I finished it in a Metallic Blue automotive paint (7 coats) and a

clear coat (5 coats) for about $20. I had the pier made out of a 36 inch

long 6" Schedule 120 cast iron pipe with a 1/4" base plate. I use an

aluminum adapter, that I machined at work from a piece of scrap, between the

pier and mount in case I ever change mounts all I have to do is machine

another adapter rather than fabricate a new pier. The pier is mounted on

some bolts sticking out of 1000 lbs of concrete that I mixed up and poured.

So, the short answer is yes, if you are willing to do some or all of the work

and have the know-how then generally you can save substantial amounts of

money by doing it yourself. On things like this and building an observatory,

my next project, I will do it myself cause I know my abilities and I hate

spending extra money on stuff I can do myself. That is why I roofed my own

house, sided it, put in new windows, added a screened in porch, deck, patio,

and privacy fence, and built my kid one of those 2 story yard forts/playhouse

things. Of course, when I am doing those things, even though I am saving

money I don't have much energy left for astronomy g>. So, pick your poison : >)))



Regards,

Andy McDavid





[Non-text portions of this message have been removed]



----------------------------

#10254 May 19, 2002

I made my pier for an LX200, so on top had a 0.5 inch UNC bolt

sticking out of the top plate welded to an 8 inch steel pipe filled

with dry sand. I machined up an aluminium adapter for the G-11 out of

a 6 inch dia aluminium alloy billet. I wanted a good fit to the base

of the G-11, mine having a diameter of 5.5130 inches and a depth of

0.9915 inches. I machined the internal size of the adapter to 5.5180

inches to a depth of 1.0 inch plus room for the head of a 0.5 inch

UNC nut and washer. The mounting screws for G-11 are 3/8 diam, at 120

deg spacing around the adapter. The reference screw is aligned with

the CWD position, or North in the northern hemisphere (South

otherwise). Drill the holes with a 3/8 inch drill with centres 0.497

inches (nominal 0.5 inches) below the edge of the adapter.



The advantage of an adapter separate to the pier is that you can

rotate it to get good azimuth alignment. I found this useful (apart

from having an existing pier) because I move the G-11 between two

sites and wish not to have to redo the polar alignment with each move

(hence the precision in the adapters).



If you have only one pier and you're going to use 6 inch dia pipe,

then you may wish to loosen up the dimensions to machine the internal

diamter of the pipe to 5.55 inches and be prepared to drill the

locating screws somewhat oversize at the nominal 1/2 inch below the

lip. Make sure you drill the holes spaced so that one hole is due

north (or south)which you might prefer to do after the pier is

screwed down (get your machinist to scribe a line at the correct

depth below the lip).



I can send you a sketch if this description isn't adequate.



Serena



--- In Losmandy_users@y..., "madmaxxx47362" dernedid@y...> wrote:

> Hi all,

>

> I'm new here and I am just coming from the LX200 camp. I am

currently

> putting in a new (first) observatory and decided to switch back to

GEM

> instead of the darn forks I've been fighting with for years. So

after

> looking for a GEM to use, looks like the G11 is going to be it. Now

> for the question, can someone tell me the inside diameter of the top

> of the upper tripod where the head fits into it? I am pricing a pier

> from LeSeur

> but, like anyone else, I'm trying to find out if I can do the pier

any

> cheaper myself,successfully that is! Thanks for all the good info on

> this group, I feel somewhat familiar with the mount already.

>

> Thanks,

> Glen







----------------------------

#10257 May 19, 2002

Can't ask for a better description than that, Thanks!!! and I hope its

warmer there than it is here, 34degF some late spring this is:-(

Thanks,

Glen

--- In Losmandy_users@y..., "serena_aussie" Serena.Steuart@b...> wrote:

> I made my pier for an LX200, so on top had a 0.5 inch UNC bolt

> sticking out of the top plate welded to an 8 inch steel pipe filled

> with dry sand. I machined up an aluminium adapter for the G-11 out of

> a 6 inch dia aluminium alloy billet. I wanted a good fit to the base

> of the G-11, mine having a diameter of 5.5130 inches and a depth of

> 0.9915 inches. I machined the internal size of the adapter to 5.5180

> inches to a depth of 1.0 inch plus room for the head of a 0.5 inch

> UNC nut and washer. The mounting screws for G-11 are 3/8 diam, at 120

> deg spacing around the adapter. The reference screw is aligned with

> the CWD position, or North in the northern hemisphere (South

> otherwise). Drill the holes with a 3/8 inch drill with centres 0.497

> inches (nominal 0.5 inches) below the edge of the adapter.

>

> The advantage of an adapter separate to the pier is that you can

> rotate it to get good azimuth alignment. I found this useful (apart

> from having an existing pier) because I move the G-11 between two

> sites and wish not to have to redo the polar alignment with each move

> (hence the precision in the adapters).

>

> If you have only one pier and you're going to use 6 inch dia pipe,

> then you may wish to loosen up the dimensions to machine the internal

> diamter of the pipe to 5.55 inches and be prepared to drill the

> locating screws somewhat oversize at the nominal 1/2 inch below the

> lip. Make sure you drill the holes spaced so that one hole is due

> north (or south)which you might prefer to do after the pier is

> screwed down (get your machinist to scribe a line at the correct

> depth below the lip).

>

> I can send you a sketch if this description isn't adequate.

>

> Serena

>

>

> --- In Losmandy_users@y..., "madmaxxx47362" dernedid@y...> wrote:

> > Hi all,

> >

> > I'm new here and I am just coming from the LX200 camp. I am

> currently

> > putting in a new (first) observatory and decided to switch back to

> GEM

> > instead of the darn forks I've been fighting with for years. So

> after

> > looking for a GEM to use, looks like the G11 is going to be it. Now

> > for the question, can someone tell me the inside diameter of the top

> > of the upper tripod where the head fits into it? I am pricing a pier

> > from LeSeur

> > but, like anyone else, I'm trying to find out if I can do the pier

> any

> > cheaper myself,successfully that is! Thanks for all the good info on

> > this group, I feel somewhat familiar with the mount already.

> >

> > Thanks,

> > Glen



----------------------------

#10258 May 20, 2002

Hi all,

>

> I'm new here and I am just coming from the LX200 camp. I am

> currently putting in a new (first) observatory and decided to

> switch back to GEM instead of the darn forks I've been fighting

> with for years. So after looking for a GEM to use, looks like

> the G11 is going to be it. Now for the question, can someone

> tell me the inside diameter of the top of the upper tripod where

> the head fits into it? I am pricing a pier from LeSeur

> but, like anyone else, I'm trying to find out if I can do the

> pier any cheaper myself,successfully that is! Thanks for all

> the good info on this group, I feel somewhat familiar with

> the mount already.

>

> Thanks,

> Glen

Did exactly this myself. The part the head wants to fit into, needs to be

5.5" ID, with three 3/8" slots descending 0.5" (centre of hole) from the

top edge - so the bottom of the slot is at 0.675" from the top of the

tube. They should then 'dogleg' by about 3/8" at this depth. The tube

needs a minimum depth of 1". Since the top of the pier I allready had was

fitted to take a LX200, I made a solid aluminium adapter plate, with this

tube on it, which can if needed also be fitted to the LX200 giant field

tripod.

The diameter should be _fractionally_ over this size (perhaps 5.515),

otherwise the fit will be too tight. Also the dogleg holes, must 'err' on

the side of being slightly too shallow rather than too deep. The actual

diameter clearance needed will vary slightly with different materials,

since (for instance) if your pier is in aluminium, both the head and the

pier should have similar thermal expansion co-efficients, but if the pier

is in a material with a lower thermal expansion rate, and the cutting is

done in cold weather, then in hot conditions the head will expand a little

more than the tube, and the fit may become uncomfortably tight.

I see another poster has said 5.530, this sounds uncomfortably 'loose' to

me. :-)



Best Wishes



----------------------------

#10271 May 20, 2002

One thing of which you need to be careful is manufacturing tolerances

when making a fitting for an unseen mating item. The parts we're

discussing are not critical and there is no particular need to hold

tight tolerances. My tripod head, for example, is not precisely round

(distorted by welding after machining) and has a minimum diameter of

5.5240 and a max of 5.5370. My G-11 base is 5.5130 diameter.

When I enquired (in a similar search) I was told 5.55 inches by

another user. The G-11 is located by resting on the top edge of the

pier (or tripod) and held laterally by the 3 screws. Once the screws

are done up the head is fixed in place even if the pier fitting is

somewhat generous in its diameter (but you'll have to do an alignment

every time you put the G-11 back on the pier).



If you want the screws to locate the the head accurately on the pier

(because you are going to take it on and off) then I suggest not

slotting the holes. Or you could drill and ream a locating pin to be

inserted before tightening the screws in a defined sequence. I don't

find completely removing the screws to be any trouble, although I

guess it does add a small risk of dropping and losing them.



You might wish to ask Scott to tell you the nominal diameter of the G-

11 base and tolerance to which he makes them. The present

contributors agree that 5.530 is a maximum diameter in their sample

set.



Serena

--- In Losmandy_users@y..., "Roger Hamlett" ttelmah@n...> wrote:

> > Hi all,

> >

> > I'm new here and I am just coming from the LX200 camp. I am

> > currently putting in a new (first) observatory and decided to

> > switch back to GEM instead of the darn forks I've been fighting

> > with for years. So after looking for a GEM to use, looks like

> > the G11 is going to be it. Now for the question, can someone

> > tell me the inside diameter of the top of the upper tripod where

> > the head fits into it? I am pricing a pier from LeSeur

> > but, like anyone else, I'm trying to find out if I can do the

> > pier any cheaper myself,successfully that is! Thanks for all

> > the good info on this group, I feel somewhat familiar with

> > the mount already.

> >

> > Thanks,

> > Glen

> Did exactly this myself. The part the head wants to fit into, needs

to be

> 5.5" ID, with three 3/8" slots descending 0.5" (centre of hole)

from the

> top edge - so the bottom of the slot is at 0.675" from the top of

the

> tube. They should then 'dogleg' by about 3/8" at this depth. The

tube

> needs a minimum depth of 1". Since the top of the pier I allready

had was

> fitted to take a LX200, I made a solid aluminium adapter plate,

with this

> tube on it, which can if needed also be fitted to the LX200 giant

field

> tripod.

> The diameter should be _fractionally_ over this size (perhaps

5.515),

> otherwise the fit will be too tight. Also the dogleg holes,

must 'err' on

> the side of being slightly too shallow rather than too deep. The

actual

> diameter clearance needed will vary slightly with different

materials,

> since (for instance) if your pier is in aluminium, both the head

and the

> pier should have similar thermal expansion co-efficients, but if

the pier

> is in a material with a lower thermal expansion rate, and the

cutting is

> done in cold weather, then in hot conditions the head will expand a

little

> more than the tube, and the fit may become uncomfortably tight.

> I see another poster has said 5.530, this sounds

uncomfortably 'loose' to

> me. :-)

>

> Best Wishes







----------------------------

#10272 May 20, 2002

In a message dated 5/19/02 9:36:15 PM Central Daylight Time,

Serena.Steuart@... writes:



> The mounting screws for G-11 are 3/8 diam, at 120

> deg spacing around the adapter. The reference screw is aligned with

> the CWD position, or North in the northern hemisphere (South

> otherwise). Drill the holes with a 3/8 inch drill with centres 0.497

> inches (nominal 0.5 inches) below the edge of the adapter.

>

>



This note reminded me of some possible idiosyncrasies (or tolerances) on some

of these dimensions. For example, my mount's 3/8-16 bolt holes are NOT 120

degrees apart! I incorrectly assumed this when designing my pier and had to

make a modification before ever getting to use it when, to my chagrin, one of

the holes was skewed about 4 degrees off of the 120 degree point. Why was

that? Hell, who knows? Maybe the machinist was having a bad day or if done

on a CNC lathe, the program had a positional error written in by mistake, or

the encoders on the CNC were faulty, or whatever. The bottom line is double

check all of your dimensions of YOUR mount before having mating parts made

up. The old adage Your Mileage May Vary certainly applies here!!!



Andy McDavid





[Non-text portions of this message have been removed]



----------------------------

#10273 May 20, 2002

In a message dated 5/20/02 4:17:49 AM Central Daylight Time,

ttelmah@... writes:



> The diameter should be _fractionally_ over this size (perhaps 5.515),

> otherwise the fit will be too tight. Also the dogleg holes, must 'err' on

> the side of being slightly too shallow rather than too deep. The actual

> diameter clearance needed will vary slightly with different materials,

> since (for instance) if your pier is in aluminium, both the head and the

> pier should have similar thermal expansion co-efficients, but if the pier

> is in a material with a lower thermal expansion rate, and the cutting is

> done in cold weather, then in hot conditions the head will expand a little

> more than the tube, and the fit may become uncomfortably tight.

> I see another poster has said 5.530, this sounds uncomfortably 'loose' to

> me. :-)

>

> Best Wishes

>



Please read my earlier post about measuring your own tripod and all mating

parts as my 5.530" was what my tripod measures with my calipers. However,

when machining my adapter, I took my mount to work and fitted the adapter to

the mount by taking a .005" out of the I.D. (after getting close but still

too small) until I had a slip fit, which is all you are after. Additionally,

I can certainly attest that even if you were .015" over on the diameter of

your adapter based on the 5.530 diameter I gave you, you would not have any

problems....that is only .0075" per side which is negligible for this

application especially since once the bolts are tightened down, the mount is

not going to move in the adapter and this is your ultimate goal.....a secure

mounting for your mount so to speak. I guess what I am trying, probably not

too clearly, to say is measure your equipment and fabricate accordingly but

don't get hung up on trying to get a line to line fit or a tolerance of plus

or minus .001. These are none moving interfaces so ultra-high precision is

not critical to functionality though sloppiness is uncalled for as well. I

will shut up now....you have received a lot of great advice and tips and I

know it will turn out well for you.



Regards,

Andy McDavid









[Non-text portions of this message have been removed]



----------------------------

#10275 May 21, 2002

One thing of which you need to be careful is manufacturing

> tolerances when making a fitting for an unseen mating item.

> The parts we're discussing are not critical and there is no

> particular need to hold tight tolerances. My tripod head,

> for example, is not precisely round (distorted by welding

> after machining) and has a minimum diameter of 5.5240 and

> a max of 5.5370. My G-11 base is 5.5130 diameter.

> When I enquired (in a similar search) I was told 5.55 inches by

> another user. The G-11 is located by resting on the top edge of

> the pier (or tripod) and held laterally by the 3 screws. Once

> the screws are done up the head is fixed in place even if the

> pier fitting is somewhat generous in its diameter (but you'll

> have to do an alignment every time you put the G-11 back on the

> pier).

Very true.

I actually suspect the part is machined to 5.50, and then becomes

'oversize', because of the anodising treatment. It is common for this to

add between about 10, and 20 thou to the size of an object (which is why

some filters are so tight - they are made 'right', but insufficient

allowance is given for the surface change when they are anodised...).

> If you want the screws to locate the the head accurately on the

> pier (because you are going to take it on and off) then I suggest

> not slotting the holes. Or you could drill and ream a locating

> pin to be inserted before tightening the screws in a defined

> sequence. I don't find completely removing the screws to be

> any trouble, although I guess it does add a small risk of

> dropping and losing them.

I use a seperate index 'peg', which I made to provide rotational aligment.

Add this to a good tube fit, and it is suprising how repeatable the

position can be. Even if you do not slot the holes, there will be

sufficient play in a normal hole to be significant, so the same approach,

of tightening up with a small constant torque applied to the head, or

another more accurate alignment point will still be needed, while the

slots make removal and insertion much quicker. :-)

> You might wish to ask Scott to tell you the nominal diameter of

> the G-11 base and tolerance to which he makes them. The present

> contributors agree that 5.530 is a maximum diameter in their

> sample set.

Unfortunately the 'manufactured' size will differ from the 'finished'

size, because of the anodising. Hence the 'best' answer is a sample of

actual heads.



Best Wishes







----------------------------

#10277 May 21, 2002

--- In Losmandy_users@y..., "Roger Hamlett" ttelmah@n...> wrote: >

> I actually suspect the part is machined to 5.50, and then becomes

> 'oversize', because of the anodising treatment. It is common for

this to > add between about 10, and 20 thou to the size of an object (which is

why



.010" to .020" is way too excessive for an anodizing thickness.. A

typical anodizing process only adds about .3 to 1.0 mil to surface

(1.0 mil being .001"). SOme hard-anodizing processes (Sulfuric/Oxalic

acid at high temperature/current) will add about 1.0 to 3.0 mill's

which is still not that much.



best regards,

Leon Aslan



----------------------------

#10289 May 21, 2002

Hey All,

Thanks for all the input, Great group. I got an E mail from a guy that

should know (Scott)says 5.550" is the size the tube specs to.After all

the input and pricing materials, I ordered a pier from one of

astromart's newest sponsors; Astro Sky. 48" tall 6"OD .5" wall with a

12" base $210 Incl. shipping. What the hey, I haven't even found a way

to buy the 6"pipe for that, and I've been looking for 2 Months. I'll

let y'all know how it works.(that is after I get a mount to put on

it!!!)

Thanks All,

Glen

--- In Losmandy_users@y..., "madmaxxx47362" dernedid@y...> wrote:

> Hi all,

>

> I'm new here and I am just coming from the LX200 camp. I am

currently

> putting in a new (first) observatory and decided to switch back to

GEM

> instead of the darn forks I've been fighting with for years. So

after

> looking for a GEM to use, looks like the G11 is going to be it. Now

> for the question, can someone tell me the inside diameter of the top

> of the upper tripod where the head fits into it? I am pricing a pier

> from LeSeur

> but, like anyone else, I'm trying to find out if I can do the pier

any

> cheaper myself,successfully that is! Thanks for all the good info on

> this group, I feel somewhat familiar with the mount already.

>

> Thanks,

> Glen



----------------------------

#10290 May 21, 2002

I had purchased a 6" AstroPier myself months ago.....mounted on a

concrete base, and have been quite happy with it. I had a wedge

mounted LX200 on it....and most recently, my G-11. I like the

Astropier because I wanted something that I could get various

mounting plates for (you may want to consider this.....different

mounting's available), in addition to side reinforcing

gussets....very important I think, from a structural end.

Pictures of my pier at www.astroimagination.com in my miniature

observatory.

I've been more than happy with it....of course, you'll need to dig a

big hole !



Also...the pier is removable if you plan it right....If I ever

relocate, I just unbolt the pier, and topsoil over the concrete. All

I'll need is 3 new anchor bolts to relocate !



Also....I investigated having this pier made from scratch, with the

same components, and I don't think I could make it cheaper than

Leseur manufacturing does it !



Rick



--- In Losmandy_users@y..., "madmaxxx47362" dernedid@y...> wrote:

> Hi all,

>

> I'm new here and I am just coming from the LX200 camp. I am

currently

> putting in a new (first) observatory and decided to switch back to

GEM

> instead of the darn forks I've been fighting with for years. So

after

> looking for a GEM to use, looks like the G11 is going to be it. Now

> for the question, can someone tell me the inside diameter of the

top

> of the upper tripod where the head fits into it? I am pricing a

pier

> from LeSeur

> but, like anyone else, I'm trying to find out if I can do the pier

any

> cheaper myself,successfully that is! Thanks for all the good info

on

> this group, I feel somewhat familiar with the mount already.

>

> Thanks,

> Glen



Contact Us
This Site's Privacy Policy
Google's privacy policies

S
e
n
i
o
r
T
u
b
e
.
o
r
g