EQ6 Latitude Lug Modification (or how to avoid bent bolts)

[laser_jock99]

Inspired by some Swedish SGL'rs here is my take on the way forward regarding how to avoid bending the altitude/latitude adjuster bolts on EQ6 mounts in Northern latitudes.

The basic problem is not that the supplied EQ6 bolts are especially weak, but that the angle they act upon the adjuster lug is not ideal for Northern latitudes. Once you get more than 45 degrees North in latitude the adjuster bolt hits the lug at an increasing acute angle. The result under load is difficulty in making adjustments and often ends up in a bent bolt.

The obvious engineering solution is to move the lug forward so the bolt hits the lug more orthogonally. I made a 40 x 30 x 20mm block of aluminium with two holes counter bored for M8 bolts.

The new lug block- notice the slight curve machined on the base to match the radius of the mount.

The next step is drill and tap two M8 holes in the EQ6 to match the block.

EQ6 securely clamped for drilling & taping.

The EQ6 casting is fairly rough so a bit of filing is necessary to make it fit the new lug block.

The new lug block in place.

Final assembly included a good dollop of metal loaded epoxy resin under the block to ensure good fit at the base and as an after thought another slug of metal loaded epoxy resin between the two lugs for added strength.

After re-assembly I can now report that latitude adjustment is now smooth and easy with no strain on the bolt at all. Important in my set-up as the OTA is over 20kg. With this modification even the supplied Synta bolts are fine. It's a pity they don't make a Northern Latitudes version of the mount?

[knobby]

Nice job

[Gina]

Yes, with an orthogonal surface to bear on the Synta bolts are fine. I've drilled the cast lug to form an orthogonal surface instead and mine works pretty well too.

[Grotemobile]

That is, one hell of of a mod.I dont think

most of us, have got the tools, or know how ,

to do something like that.Very good through.

Steve

[JamesF]

Looks good. Is there any access to the inside of the mount body where the new block attaches, or is that all sealed off?

James

[Bizibilder]

That looks like a very useful modification. Is there any particular reason that you chose to drill into the main casting? Rather than drilling into the casting (and not being sure what is in there plus the swarf that will be rattling about for ever) could you not have shaped and drilled the block to fit onto the working face of the EQ6 lug itself? Just a thought rather than any criticism of you design.

[nightvision]

Nice job, I thought this type of mode required the removal of the original lug?

[JamesF]

Nice job, I thought this type of mode required the removal of the original lug?

The north side adjustment bolt probably still has to bear on the original lug, otherwise you'd end up with the same bendy-bolt problem in reverse.

James

[1parsec]

Nice work.

I reckon a small thrust bearing fitted to the face of your aluminium block would make the adjustment even easier.

Dave.

[nightvision]

The north side adjustment bolt probably still has to bear on the original lug, otherwise you'd end up with the same bendy-bolt problem in reverse.

James

Ahh.. thanks James, that makes sense.

[laser_jock99]

Looks good. Is there any access to the inside of the mount body where the new block attaches, or is that all sealed off?

James

Yes there are two rather small slots either side of the main casting. You could access the rear of the M8 bolts I used if you had very nimble fingers!

That looks like a very useful modification. Is there any particular reason that you chose to drill into the main casting? Rather than drilling into the casting (and not being sure what is in there plus the swarf that will be rattling about for ever) could you not have shaped and drilled the block to fit onto the working face of the EQ6 lug itself? Just a thought rather than any criticism of you design.

I thought it was more straight forward to make a new block as it needs to be quite far from the original lug to make a difference. You make a good point about swarf falling inwards. I stuffed a rag into the above slots to catch anything coming through. Though I'm sure a small amount will have made it onto the RA shaft.

Nice work.

I reckon a small thrust bearing fitted to the face of your aluminium block would make the adjustment even easier.

Dave.

When I upgrade my other EQ6 I might machine a vee groove or even a round slot into the bearing face for added stability. The problem though would be centring it to the incoming bolt. Given the design/quality of these mounts I wouldn't assume it was necessarily in the middle!! I can't think of an easy way to align this other than checking where the wear marks on the old lug?

[Gina]

I used the threaded hole where the adjuster bolt goes to get the position right when I drilled the lug having set the altitude to 51 degrees (local lattitude) on the scale. Having drilled a smaller hole, I opened it up to larger than the bolt and took care to get the angle the same as the bolt would be at. This not only gives a surface at the right angle but also something to stop the bolt wandering and possibly bending. I lubricated the bolt end and threads with a small amount of moly grease whuch makes it very smooth (very low friction grease for sliding surfaces). Of course the mount is now "personalised" to this lattitude but I'm very unlikely to want to sell it so I'm not worried. The result is a great success

[JamesF]

Even if you do want to sell it on it's not going to be too far out for anyone in the UK.

James

[tonedeaf]

great mod!!!11!11!

ok have to ask my workshop here in my company, if there is a possibility to make such a milling job for me

[laser_jock99]

I have now added a repositioned latitude lug on my second EQ6 mount. So some further thoughts on the mod if anyone else is planning this:

Stuff the cavity well with rag or tissue to prevent swarf falling onto the RA axis

The newer EQ6 casting is even more curved than my old one- so plenty of filing is needed to make it flat enough to seat the block!

My second design featured 3 x M6 bolts. Drill and tap the middle first, bolt this down and square the block up to the mount. Then drill & tap the other two holes through the block. This way I ended up fairly square to the acting bolt.

Again a good slug of epoxy putty between the two lugs for added stability. Notice also the layer of tape on the vice jaws to protect the mount paintwork.

The mount can then be inverted and the rag removed from the cavity- there's a small pile of swarf to vacuum out.

A full 30mm has to be removed from the South adjuster bolt so it cleared the polar finder dome.

When re-grinding the dome on the bolt it needs to well centred. To achieve this a guide hole in a block, clamped to grinder is invaluable.

[Gina]

Looks good:)

After all the messing about with my NEQ6 I did an accurate PA last night using AstroTortilla and quite easily got to within 2 arcmin in both directions. Altitude is now a dream (So is azimuth.) I was able to do a 5m Ha exposure unguided without noticeable egging of stars.

[JamesF]

That's a very neat mod

James

[astrorg]

On 27/05/2013 at 21:43, laser_jock99 said:

Inspired by some Swedish SGL'rs here is my take on the way forward regarding how to avoid bending the altitude/latitude adjuster bolts on EQ6 mounts in Northern latitudes.

The basic problem is not that the supplied EQ6 bolts are especially weak, but that the angle they act upon the adjuster lug is not ideal for Northern latitudes. Once you get more than 45 degrees North in latitude the adjuster bolt hits the lug at an increasing acute angle. The result under load is difficulty in making adjustments and often ends up in a bent bolt.

The obvious engineering solution is to move the lug forward so the bolt hits the lug more orthogonally. I made a 40 x 30 x 20mm block of aluminium with two holes counter bored for M8 bolts.

The new lug block- notice the slight curve machined on the base to match the radius of the mount.

The next step is drill and tap two M8 holes in the EQ6 to match the block.

EQ6 securely clamped for drilling & taping.

The EQ6 casting is fairly rough so a bit of filing is necessary to make it fit the new lug block.

The new lug block in place.

Final assembly included a good dollop of metal loaded epoxy resin under the block to ensure good fit at the base and as an after thought another slug of metal loaded epoxy resin between the two lugs for added strength.

After re-assembly I can now report that latitude adjustment is now smooth and easy with no strain on the bolt at all. Important in my set-up as the OTA is over 20kg. With this modification even the supplied Synta bolts are fine. It's a pity they don't make a Northern Latitudes version of the mount?

Like the 'simple' approach and I am going to do it too - I too have around 15- 21 Kg varable and it is a lot of strain on the screws at that angle.

I did replace the bolts with home-made ones [!] and it improved, but still to heavy to turn - notw it is time to a 'proper' modification and it is certainly the cheapest, if yu are a DIYer and I am too.

Got the Aluminum bar [block] and will do it as soon as I have time.

The only problem I have is my garage is FULL and in need of re-assessing as soon as I can ... already got all I need to re-furnish it and place tools properly [again]!

It is needed once in a while.

;p]