Celestron EdgeHD 1100 Dovetail bolt sizes?

[oymd]

I have an extra CGE losmandy dovetail that I am trying to fit to the TOP of my Edge 11.

There are four holes I can use on the top of the OTA. Does anyone know what bolt sizes I should use?

I think they are Metric M4? or are they for UNC Whitworth bolts?

I want to use SOCKET HEAD bolts, but the ones I have do not fit. Width seems to be fine, but I think the thread does not match?

Also, I think the FRONT ones at the corrector plate are LONGER?

I had a look at the ones on the BOTTOM, where I have a Primaluce Lab Dovetail with radius blocks. The FRONT ones are 20mm and the REAR ones are 15mm, but do not remember what thread type they are and not sure of size? I used an M4 Allen key to undo them, so I suppose they are M4?

Thanks

[oymd]

anyone?

[inFINNity Deck]

Hi Oymd,

I have listed them here:

https://www.cloudynights.com/topic/666441-celestron-c11-edge-hd-bolts/?fromsearch=1

Nicolàs

[oymd]

50 minutes ago, inFINNity Deck said:

Hi Oymd,

I have listed them here:

https://www.cloudynights.com/topic/666441-celestron-c11-edge-hd-bolts/?fromsearch=1

Nicolàs

Thanks Nicolas

So, they seem to be all UNC?

In your post you mentioned:

dovetails: 3/16" UNC x 1/2", 3/4" and 1" (depending on which type of dovetail plate was installed)

I'm a bit confused?

There are 4 holes to attach a dovetail. Are they ALL 3/16" in size?

I assume the two FRONT ones near the corrector plate will be LONGER? so 3/4" for the front two holes and 1/2" for the rear holes? Obviously the length will depend on the dovetail and how far off it is from the hole. The dovetail I will be using is the Celestron Losmandy CGE orange dovetail.

Many thanks

Ossi

 

 

[oymd]

1 hour ago, inFINNity Deck said:

Hi Oymd,

I have listed them here:

https://www.cloudynights.com/topic/666441-celestron-c11-edge-hd-bolts/?fromsearch=1

Nicolàs

And 3/16 UNC is the diameter? I can’t find that. Only 3/8-16 UNC. Is that the one?

I thought UNC bolts have a fraction followed by a number for measurements like: 1/4-20 UNC?

so, by 3/16, what do you mean?

3/16-20? Or 3/8-16 etc?

many thanks

 

 

Edited December 4, 2021 by oymd

[JamesF]

To the best of my knowledge UNC threads are specified by diameter and the number of threads per inch meaning that 3/8-16 would be a 3/8" diameter thread with 16 threads per inch, but I'm fairly sure that all threads of the same diameter have the same number of threads per inch so just giving the diameter (3/16" in this case) should be sufficient to get the correct thread.

That said, I thought all UNC threads smaller  than 1/4" diameter were given numbers and tpi rather than sizes, so I'm not sure what 3/16" might actually be if you wanted to buy some.  It might be #10-24, but don't quote me on that.

A 3/16" BSW thread should also fit, I think.  BSW and UNC threads are mostly interchangeable.

I hate non-metric threads

James

[oymd]

49 minutes ago, JamesF said:

To the best of my knowledge UNC threads are specified by diameter and the number of threads per inch meaning that 3/8-16 would be a 3/8" diameter thread with 16 threads per inch, but I'm fairly sure that all threads of the same diameter have the same number of threads per inch so just giving the diameter (3/16" in this case) should be sufficient to get the correct thread.

That said, I thought all UNC threads smaller  than 1/4" diameter were given numbers and tpi rather than sizes, so I'm not sure what 3/16" might actually be if you wanted to buy some.  It might be #10-24, but don't quote me on that.

A 3/16" BSW thread should also fit, I think.  BSW and UNC threads are mostly interchangeable.

I hate non-metric threads

James

Thanks James

yes, agreed. Imperial threads are just stupid!!!

So, what do you think I should order?

Nicholas just mentions 3/16”. What should I order?

😂

[JamesF]

A hunt around on the net suggests that 3/16" BSW is interchangeable with #10-24 UNC and if the same diameters of UNC and BSW are also supposed to be interchangeable then some #10-24 UNC bolts should do the job I think.

Could be worth waiting to see if @inFINNity Deck can confirm the sizing though.

James

[inFINNity Deck]

Hi Ossi,

officially these screws are 10-24 (3/16), so number 10, 24TPI, 3/16" diameter. I uses them for all four holes if I remember well. The length depends on whether you use the original orange dovetall or an ADM one.

Nicolàs

[inFINNity Deck]

4 minutes ago, JamesF said:

A hunt around on the net suggests that 3/16" BSW is interchangeable with #10-24 UNC and if the same diameters of UNC and BSW are also supposed to be interchangeable then some #10-24 UNC bolts should do the job I think.

BSW and UNC are more or less interchangeable, but not exactly (different rounding of the threads and minute difference in diameter). Being made of aluminium it is no problem inserting the wrong type in the holes. I noticed that on my C11 a variety of threads was used: UNC, BSW and metric, but I cannot say for sure which ones were original. As BSW are very hard to get at these sizes here in the Netherlands I decided to order UNC for all non-metric screws.

Nicolàs

 

[JamesF]

In that case I'd suggest trying #10-24 UNC bolts.  They're available on ebay for a pound or three in small pack sizes, so if it isn't the right size you shouldn't have wasted too much cash.

James

[oymd]

6 minutes ago, JamesF said:

In that case I'd suggest trying #10-24 UNC bolts.  They're available on ebay for a pound or three in small pack sizes, so if it isn't the right size you shouldn't have wasted too much cash.

James

 

14 minutes ago, inFINNity Deck said:

BSW and UNC are more or less interchangeable, but not exactly (different rounding of the threads and minute difference in diameter). Being made of aluminium it is no problem inserting the wrong type in the holes. I noticed that on my C11 a variety of threads was used: UNC, BSW and metric, but I cannot say for sure which ones were original. As BSW are very hard to get at these sizes here in the Netherlands I decided to order UNC for all non-metric screws.

Nicolàs

 

Thanks Nicolas and James for your prompt help and response!!

FOR THE LOVE OF GOD, why do telescope manufacturers confuse us so much!!!!

Isn't the hobby hard enough as is!!!!???

😀

[inFINNity Deck]

31 minutes ago, oymd said:

FOR THE LOVE OF GOD, why do telescope manufacturers confuse us so much!!!!

Isn't the hobby hard enough as is!!!!???

😀

That is just to avoid that we get bored too soon... 😉

Nicolàs

[oymd]

On 04/12/2021 at 17:01, JamesF said:

In that case I'd suggest trying #10-24 UNC bolts.  They're available on ebay for a pound or three in small pack sizes, so if it isn't the right size you shouldn't have wasted too much cash.

James

 

On 04/12/2021 at 17:41, inFINNity Deck said:

That is just to avoid that we get bored too soon... 😉

Nicolàs

Good morning James and Nicolas

It seems my issues continue!

Based on our conversation here on this thread, I ordered a bunch of  UNC #10-24 socket cap bolts on Ebay. I ordered 5 different lengths, ranging from under 1/2 an inch all the way to one inch. ALL BLACK to avoid reflections.

Unfortunately, NONE of them screw in completely!!?? They all screw about 3 turns, and then stop.

Very frustrating.

Well, I then ordered an IMPERIAL thread gauge from Amazon (Its actually a BSW British Standard Whitworth) which is technically 55 degress, as opposed to UNC 60 degrees, but was told its almost exactly the same as a UNC thread gauge imported from the USA.

Anyways, they all measured correctly at 24 TPI?

So, I took out the 4 bolts that actually came with the scope, and I have some interesting findings to report:

1- The two screws at the BACK of the OTA near the mirror are indeed 24 TPI

2- The two screws at the FRONT of the OTA near the corrector plate are 32 TPI?!! They are NOT 24 TPI? 

Looking at the UNC charts, there are only TWO screw sizes with 32 TPI: #6-32 and #8-32

But, arent those two of a SMALLER diameter? The screws in the OTA have different TPI, but of different TPI.

Could the two FRONT holes on my OTA be metric?

[oymd]

On 04/12/2021 at 17:01, JamesF said:

In that case I'd suggest trying #10-24 UNC bolts.  They're available on ebay for a pound or three in small pack sizes, so if it isn't the right size you shouldn't have wasted too much cash.

James

Indeed, I now have a bunch of #10-24 bolts, 50 to be exact, and NONE of them fit any of the 4 holes?!

I have just ordered another bunch of #8-32 bolts to try at the FRONT end of the OTA

[inFINNity Deck]

My C11 is a C11 EdgeHD with mirror-locks. It could be that other C11s use other threads. The only other thing I can imagine is that, because I bought my SCT second hand, that the previous owner may have changed the threads, but currently all four currently are #10 24TPI.

32TPI converts to a pitch of 0.79mm, not a standard metric thread (there are metric fine threads that have this pitch, but those I do not expect on this scope).

Nicolàs

[Oldfort]

On the C8, the fasteners are 8-32.  The edge 11 looks the same.
There are a few suppliers in the UK for Imperial sizes, eg Accu and Westfield fasteners. 

Edited December 9, 2021 by Oldfort

[oymd]

31 minutes ago, Oldfort said:

On the C8, the fasteners are 8-32.  The edge 11 looks the same.
There are a few suppliers in the UK for Imperial sizes, eg Accu and Westfield fasteners. 

oh..seems we are getting somewhere!!

So it seems my Imperial gauge works!?

But I think that #8-32 are only the FRONT ones, as the Back ones look like they have a COARSER THREAD PITCH??

Have a look at the pic above where I took a close up of the Philips screws that were in the OTA.

The back ones certainly look like they have a coarser pitch compared to the front ones?

[Oldfort]

On the C8 the front and back fasteners are 8-32.  For the edge 11, it's hard to tell from the photos, but I remeber being surprised to find all the holes were the same in my C8 (except those holding the end parts to the tube).

 

I have found this gauge quite useful (even though it's not very robust) and cheap.  It has holes for the diameters ar well as the thread sizes, metric and imperial.

https://www.axminstertools.com/axminster-4-piece-universal-thread-gauge-set-102551

[oymd]

58 minutes ago, Oldfort said:

On the C8 the front and back fasteners are 8-32.  For the edge 11, it's hard to tell from the photos, but I remeber being surprised to find all the holes were the same in my C8 (except those holding the end parts to the tube).

 

I have found this gauge quite useful (even though it's not very robust) and cheap.  It has holes for the diameters ar well as the thread sizes, metric and imperial.

https://www.axminstertools.com/axminster-4-piece-universal-thread-gauge-set-102551

A very similar one is in the post already on its way.

 

[oymd]

9 hours ago, Oldfort said:

On the C8 the front and back fasteners are 8-32.  For the edge 11, it's hard to tell from the photos, but I remeber being surprised to find all the holes were the same in my C8 (except those holding the end parts to the tube).

 

I have found this gauge quite useful (even though it's not very robust) and cheap.  It has holes for the diameters ar well as the thread sizes, metric and imperial.

https://www.axminstertools.com/axminster-4-piece-universal-thread-gauge-set-102551

My gauge plates arrived today.

I think I ordered wrong ones, as it says DRILL GAUGE, and does not have the same designations like the one you advised. Guess I will also order the one from Aximinstertools. The plates I received do not have the #6, #8, #10 etc designations, but rather ALL fractions for the IMPERIAL sizes.

I need your advise regarding judging the diameter of a bolt using these plate gauges.

Should the bolt FREELY go through a hole for the correct size, or should it SCREW into the correct hole?

 

Edited December 9, 2021 by oymd

[Oldfort]

The plates are not threaded, so the bolt just pushes through.  Just find the smallest hole that works, without forcing things.  It helps to know if you are dealing with imperial or metric, which you do, but if not you can figure this from the threading.

BTW, I should have mentioned that the Axminster gauges are a bit flimsy, just to manage your expectations.

 

Good luck

Edited December 10, 2021 by Oldfort