Sheared Allen Bolt

[glowjet]

I have been following your dilemma, looks as if your only solution now is to completely drill out the old socket head cap screw. Just an idea, but If you can fix the scope body parallel, at a hight so as you can drill from underneath, this may help with bits going everywhere. Once out remove the front end, you can give the whole thing a thorough clean. If you have been able to keep your hole to 4mm you can re-tap for 5M and while you are at it you can do all the others so that they look the same, replace with the correct length, grade 2 or if you want the best, marine grade 4 stainless socket head cap screws. Best of luck, whatever you do

[biondi]

Hi glowjet, appreciate the input!

I found four new M4 bolts (the same size as the previous ones but they look like Stainless Steel, I presume they're M4 as they are 4mm) on an old dovetail which was handy. The hole I have is too tight for this so I'm considering getting a t-type tap wrench and an M4 tap.

So much pain for such a silly thing - I'm so annoyed with myself for not being more careful when tightening this bolt but it's something you do often and it's never happened before.

[jetstream]

Initially we use old dentists drills-very small & different ones to choose from,used in a Dremel tool or air die grinder-and then carefully cut a screw driver slot in the bolt.Now as has been suggested it needs to be drilled out.....would a drill press be better than hand bombing the drill?Soft jawes on press vise,hold it nicely but not too much squeeze.And use a 135 degree SPLIT POINT drill bit- they don't need a pilot hole and tend to stay straighter when feeding bit.They work.I hope this helps.

[jetstream]

Use the right size bit for the tap.Important.

[biondi]

If I had a handheld impending disaster detector it would now be bleeping.

Sent from my iPad using Tapatalk

[Tinker1947]

If your going to tape out a 4mm thread, buy the right size drill bit to make the hole, if you don't have a Bench Drill to get the hole straight use a piece of timber with the hole drill in it, then start the hole just enough to stop the drill wondering, pass it through the wood and into the indent then hold or clamp the wood this will give you a nice straight hole provided the hole in the wood is straight, use the same hole to tape the thread this keeps the tap level,,,,or pop over to my place i have the taps,bench drill ect... ect i will do it...

[glowjet]

You can check your screws to see if they are stainless with a magnet, they have very little attraction. No need to invest in 4mm HSS taps for the alloy, you can use the cheaper carbon steel. Your tapping drill for 4mm I.S.O. metric course should be 3.30mm 0.1299" If the hole is bigger than that, you may have to have consider M5, as I do not suppose the OTA tube is all that thick.

However, another trick I have used, would be to use Areldite rapid, 5min epoxy to affix a 4mm stainless nut on the inside, in the event that you strip it down, having removed the damaged bolt, align the holes with a matchstick, hold the nut on with Cellotape until the resin sets. Paint the repair with matt black paint. It will hold for you to put the screw back and tighten up, as I do not suppose you will be taking it apart again in any hurry. I should not kick yourself too hard, as these accidents do happen, we all do daft things we regret, so long as you are able to effect a repair and get yourself out of trouble is the main thing

[RT65CB-SWL]

I had a similar situation when my ETX105 flip mirror assembly decided to hit the ground first. It put a nice crack in the plastic and two loose 6-32 panhead bolts and one seized. It eventually came out after the drill bit made a bigger hole in the plastic. I then used a set of mole-grips on what was left of the bolt and carefully unscrewed it out.

Phoned 'Telescope House'. Very helpful but no luck on replacement.

Phoned 'Meade'. Complete waste of time.

Phone insurance company. Not interested.

As the plastic was a bit of a mess, I did a plan for a new back to appoximate dimensions and took it to a local engineering workshop. I did not know what spacing the screw and focusser holes were so I left them the 'plastic' as a template. They made the part with the holes in the correct places.

Well the ETX 'lives', but I think collimation is slightly out as I get a 'slight' flare to one side of the bright planets, (ie Venus, Jupiter & Saturn), but not when I am looking at the stars as I appear to be getting a good even 'doughnut' shape when it is out of focus. I think the Moon is OK too!

Apologies in advance if I have hijacked the thread, (...pun not intended)!

[biondi]

Well, the sheared bolt issue has been sorted.

Today I went up to Tinker1947 in North Norfolk who kindly offered to take a look at it. What a nice chap. One extractor bolt and two drill bits were lost during this battle. However, they died heroically. The OTA is now as good as new but I come back home feeling somewhat envious of your equipment John

Thanks again for sorting out my problem and accommodating myself, my wife and a 6 year old who wanted to go to the beach! Seeing how you fixed this today I know that I would never have been able to do this without the right tools, a lesson learnt!

Matt

[Tinker1947]

Pleasure you meet you and help sort out the problem, and i have 4 real Ales to drink with my Sunday dinner,,,Thank you.....

[glowjet]

Very pleased you managed to get things sorted Matt. Engineering knowledge, a workshop and an offer of friendly member assistance, in times of trouble, is worth much these days. It is quite astounding the help SGL is able to provide to the membership, just think where you might have been, if you had not been a member of this community