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Drilling holes in XT8 Dob

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#26 Mxplx2

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Posted 13 January 2013 - 07:52 PM

There are glues like pliobond and silicone adhesive that hold well under normal use, but can be removed with a little effort, in case your not happy with the knob.

#27 JLovell

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Posted 13 January 2013 - 10:12 PM

I love the knob on mine, and use it exactly as Jon described, one hand on the knob for alt, and one on the left side bearing of the base. I can push with one hand and pull with the other to give the scope a pure torque, and it makes the az movements smoother and much easier to control.

The knob also helped my instantly visualize how to move my scope to track objects. When I grab the knob when looking through the scope, I imaging I'm reaching into what I'm viewing, and grabbing the star or planet, and that I'm dragging it around. As soon as I realized that, I could track everything quite easily. Before that, I'd frequently go the wrong way.

#28 Bill Weir

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Posted 13 January 2013 - 11:07 PM

Getting back to the drilling fear. Get a 1" thick block of wood and drill through it. Now you have something to hold against the tube while wrapping your fingers into the tube. It will guide the bit and prevent it from slipping. Straddle the tube to hold it steady and away you go. I've done this when I drilled a couple of holes when replacing the focuser on my 6" Orion.

Holding the block of wood on the inside of the tube gave some support when doing a light tap do set the point before begining the drilling.

Bill

#29 Achernar

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Posted 14 January 2013 - 08:13 AM

I wouldn't use a center punch, but a piece of angle iron in the shape of a C with a hole drilled through it would work as a drill guide. So would a piece of wood with a vee cut out of one side, with the guide hole drilled at the vee. Start with a small drill bit to make a pilot hole, then follow up with the full sized drill bit. An alternative is to use a drill press, you would want to make a cradle to keep the tube from moving. If you go that route, you will want to have someone assist you in holding the tube. Otherwise, a cordless or corded hand held drill is how I would do it. It goes without saying that I would remove the optics before doing this. Just remove the spider and primary mirror cell with the mirrors in them, drill your hole, add the navigation handle, then replace and re-collimate the optics in the tube.

Taras

#30 kenrenard

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Posted 14 January 2013 - 09:36 AM

Clare,
I have the same XT8. After reading this. I am going to put a knob on my tube as well. Hope your drilling goes smooth.

#31 JLovell

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Posted 14 January 2013 - 10:20 AM

Another thought... Try removing one of the screws that hold the metal ring at the top of the tube. My scope has such a screw about 1/4 inch away from the knob mine came with. Take that screw to a hardware store to figure out the size and thread pitch. Get another screw the same size and pitch, and the type of knob with a hole all the way through so that the screw installs in that hole as opposed to from the inside. Get the new screw of appropriate length that it protrudes from the knob exactly the length of the original screw minus the head. Then simply screw the new screw with the knob back into the hole that is already there. No drilling required!

#32 SteveG

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Posted 14 January 2013 - 01:50 PM

As others have said, it's an easy install. Use masking tape on the inside, start with a little hole and then drill the larger hole. Here's a nice little knob:
http://www.opticsmar...and-tweaks.html

#33 NeilMac

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Posted 14 January 2013 - 02:19 PM

As what SteveG says. When dealing with slippery surfaces, you tape them then use a sharp small (1mm) drill used for metals, slowly apply pressing lightly. Then the size you require for the screw mount.

#34 stargazer424

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Posted 14 January 2013 - 03:28 PM

Just the title of this post makes me cringe. I can't imagine drilling holes in mine...good luck, however you do it. :confused:

#35 Allan...

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Posted 15 January 2013 - 06:09 PM

Just ordered one of those Soft grip guide knobs; thanks for the tip, Steve. I could've gone to the hardware store and picked out something that would work (and cost less) but this one looks good and I know it will do the job. Got lots of advice now on the drilling job, so not worried. thanks, Clare :)

#36 kenrenard

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Posted 18 January 2013 - 06:42 AM

Clare,
I installed the same knob last night. I attached some pictures and hopefully this helps anyone thinking of doing the same.

The first step was removing the band across the top of the tube. This is held in place with some phillips head screws. Next I removed the tube from the bas and set the tube open end down on a couch (My wife was not crazy about this idea!) I used electrical tape on both sides where I was going to drill and started with the smallest drill bit I have.

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#37 kenrenard

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Posted 18 January 2013 - 06:52 AM

The next step I moved to a 7/32 bit which was perfect size for the knob screw. I used a damp paper towel to catch any drill droppings from the end. Then I used another wet paper towel followed by a dry one to wipe out the tube. Installing the knob was one screw so that was easy.

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#38 kenrenard

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Posted 18 January 2013 - 07:00 AM

The finished product is shown below. I ended up placing the knob a bit off center which is where I wanted it for movements while at the eyepiece. I ordered the knob from opticsmart.com and it arrived in less than two days. I also installed a set of Bob's knobs which were extremely easy to install. I think the both items are easy upgrades for a beginner to install.

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#39 NeilMac

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Posted 18 January 2013 - 10:45 AM

I like your secondary mirror adjustment screws :)
Good job on the knob :)

#40 kenrenard

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Posted 18 January 2013 - 10:49 AM

Thanks I ordered the secondary screws from Bob's Knobs they are the 30mm length knobs. Bob e-mailed me the day I ordered and verified the right length. They arrived in 2 days with instructions they took only a few minutes to install.

#41 csrlice12

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Posted 18 January 2013 - 12:04 PM

I was wondering how best to (if I dare) drill a hole in my XT8 OTA....would like to put on one of those rubber navigation knobs on the top end (like the ones that come with the Intelliscopes and even on the XT4.5). Not sure why they left them off the classic models. I find that grabbing the tube isn't the best method. Think the knob would simplify things. I have visions of starting the drill bit and having it SLIP and oops....one nasty scratch on the OTA. One cant really expect to use a centre punch to start the hole. Anyone got any fool proof methods up their sleeve? thanks, Clare :)


Be careful, its a slippery slope. Yea, it all starts out with a drill bit; before you know it, you'll be using chain saws and arc welders........... :roflmao:

To be truthful, I use that knob maybe 30% of the time. Usually AFTER i've gotten the object in the FOV for nudging.

#42 C_Moon

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Posted 20 January 2013 - 06:55 PM

I've drilled a hole in my XT8 for a wire to pass through to a homemade secondary dew heater. I did not remove either the primary or secondary. I put the scope in horizontal position, with the open end slightly pointed towards the ground. I used a sharp drill bit and was able to drill the hole very quickly with no trouble at the size I wanted the first time. There were very few shavings, but they were easy to sweep out and none got on the secondary or even near the primary.

I was nervous about this but fortunate to have an experienced friend from my astro club help me out.

Good luck!

#43 Allan...

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Posted 01 February 2013 - 08:19 PM

I got up the nerve today to drill the 1/4" hole in the OTA of my XT8. Masking tape; made up a jig, and started with a very small drill bit; and moved slowly upwards until I ended up with 1/4". The OTA was surpisingly tough to drill through; (either that or my drill bits were very dull..lol). Pointed it downward to avoid filings inside; removed the outer trim ring and did the deed. The finished product is great; now all I need is clear skies...! Thanks, Clare

#44 kenrenard

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Posted 01 February 2013 - 08:22 PM

I got up the nerve today to drill the 1/4" hole in the OTA of my XT8. Masking tape; made up a jig, and started with a very small drill bit; and moved slowly upwards until I ended up with 1/4". The OTA was surpisingly tough to drill through; (either that or my drill bits were very dull..lol). Pointed it downward to avoid filings inside; removed the outer trim ring and did the deed. The finished product is great; now all I need is clear skies...! Thanks, Clare


Clare,
I agree it was tough I thought as well. I had a pretty sharp bit. The handle is really nice I find myself using it all the time. Glad you got the hole drilled.


Ken

#45 Allan...

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Posted 01 February 2013 - 08:23 PM

I got up the nerve today to drill the 1/4" hole in the OTA (started off smaller and moved slowly upwards toward the 1/4"); used masking tape, made a wooden jig and all went well. The OTA was surprisinly tough to drill through (either that or my drill bits were very dull...lol). All worked out in the end. Navigation knob installed and looks great. Now all I need is clear skies to try it out. thanks, Clare :cool:

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#46 NeilMac

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Posted 01 February 2013 - 11:40 PM

if i was to put one on i would choose the 3:00 position, was thinking about it a few days ago. the 6:00 position i rarely use and normally move it from the side position.

#47 Allan...

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Posted 02 February 2013 - 04:27 PM

Neil, if you have an XT8I, you should have one on your scope already. Isn't it in about the 5:30 O'clock position? Mine is in around 5 O'clock position, a bit closer to the spider van knob than I wanted but its exactly where the Manufacturer reccommended to put it (2" down and 2.5" toward you, from the bottom seam). It works fine for me. I think that if I had put it at 3 o'clock, my arm would get cramped from being bent at the elbow too much. Just my thoughts on it. Personal preference, obviously. I didn't want to get too close to that bottom seam when drilling. Clare :)

#48 NeilMac

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Posted 02 February 2013 - 04:31 PM

yes, its at 6 oclock position. Il check next time.

#49 NeilMac

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Posted 03 February 2013 - 11:49 AM

yup 5:30 is the standard.

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