 All the parts in the kit |
 Replacement Az Jacking bars and bearings |
 Roller thrust bearings are used for ALT jacking bars. |
 Tilt-plate pivots. |
 Slip-plate and Wedge Mounting T-bolts |
 Tilt-plate clamping T-bolts |
 Adjustable Azimuth Dog |
 Optional Eyepiece Rack |
* The original parts are modified when the upgrade is carried out in the workshop, complete replacements are supplied with an upgrade kit.
** Additional bushes for this bearing can ONLY be fitted in my workshop, in the kit a 3/8" plain steel pin is supplied to fit the existing hole.
*** This part needs two holes drilling and tapping 5mm to be fitted. It is not essential for correct functioning of the wedge adjustments.
Dismantling the wedge:
The first job is to dismantle the superwedge, and the most difficult part of this is in releasing the various screwed fasteners (nuts, screws, bolts etc.,) which Meade often hold in place using Loctite thread-locking compound. It is possible simply to use enough torque to overcome the locking compound, or alternatively, you can heat the joint to about 250 deg C whereupon the Loctite bond breaks down (thus releasing the thread).
For the Azimuth adjuster I simply use a pair of ring-spanners, one placed on the right-hand Acorn nut, and the other on the left. Apply enough torque and one of them will give way first (!) and unscrew. Still holding the other with the spanner, unscrew the knob and then the locking nut from the loosened side and remove the two spring washers. Unscrew the adjuster using the remaining knob until the azimuth dog (the thing with the pin that engages the slot) comes off the end of the rod, and then you can remove the azimuth all-thread from the wedge.
The ALT adjuster is simply unscrewed counter-clockwise until it's all-thread disengages from the tilt-plate jacking bar (remove the side clamp bolts first). Remove the small screw holding the scale marker, then remove the hex-spacer bar which supports it. This will probably not be replaced as, in my opinion, it does absolutely nothing useful anyway! In addition, with the marker in place it's difficult to get both clamping T-bolts in that side (one, but not both). Finally, remove the two pivot bolts attaching the tilt-plate to the wedge and the tilt-plate will come away.
Turn the wedge upside-down and remove the 8 Allen bolts holding the wedge side-plates in place. Again, be prepared for these bolts to be held in place by Loctite. The fixed ALT jacking bar will then come free from the recesses that hold it in place. At this point, use the 2 spanners again to remove the 2 locking nuts and washers, then remove the ALT all-thread from the jacking bar (The jacking bar will be replaced by a new part).
Installing the Upgrade Kit:
Locate the new fixed ALT jacking bar with it's two large bronze bushes and spacers. Check that the bushes slip into the recesses in the wedge side-plates (I make them an easy fit as the Epoxy Resin be holding them in place and correcting for any alignment errors). Temporarily re-attach the two wedge side-plates using just a single bolt on each side (use the two bolt holes at the far end, opposite to where the fixed jacking bar is). Don't tighten these bolts up - leave them loose enough so that the side-plates are free to swing outward. Now it is possible to insert the new bar, and with the bushes inserted into the recesses push the two side-plates together trapping them between. Temporarily, put the FRONT two side-plate retaining bolts in place, and tighten them up. You can now check the side clearance of the jacking bar when held by the new bearing bushes. There should be about 1/16" of free sideways travel (i.e., end-float) to allow the ALT all-thread to line up with the threaded insert, if there is more clearance than this, and there probably will be, then you will need to add a spacer (1" dia, 5/8" bore x 1/16" thick) to each end of the jacking bar. A second pair of spacers is provided should they be necessary.
 Large bronze bearings used for the fixed jacking bar. |
When you are happy that all the components fit, and you have determined the number of spacers required, you can proceed to cement the bushes in place. Remove the front two side-plate bolts again so you can release the jacking bar, then mix a small amount of Epoxy cement according to the instructions on the box (use equal amounts of resin and hardener, mix thoroughly). Put a *little* smear of grease on the 5/8" diameter steel stub axles on each end of the fixed jacking bar (this is merely a safety precaution in case the Epoxy should somehow get into the bearing - it will prevent the bearing from siezing up), and then place the spacers and bronze bushes on the ends. Put a thin, even layer of Epoxy on the outer surfaces of the bronze bushes where they will contact the wedge side-plates, sufficient to completely fill any gap, and then press them home into the recesses - and at the same time close the two side-plates together trapping the jacking bar in place. You can trim away any excess epoxy cement with a craft-knife after it begins to set (but before it hardens completely). Screw in the front two bolts again, and then tighten all four bolts up. This procedure will ensure the bushes are held in correct alignment whilst the Epoxy sets, you will need to put the wedge aside for 3-4 hours while the cement hardens.
A slightly different technique is used for the tilt-plate jacking bar. Because the bearing lugs are cast integral with the tilt-plate, and also the outer faces of these lugs are flush with the inside faces of the wedge side-plates, it is thus not possible to permanently fix *both* bronze bearing bushes in place and then get the jacking bar into position. Instead, plain cylindrical bushes are used which can pass right through the holes in the lugs during assembly. The replacement bar supplied with the kit has a stainless steel threaded insert (1/2" x 13 tpi) into which the ALT adjuster threads. In order to fit this bar it's necessary to unscrew the nuts holding the insert in place and remove it, together with the seats and washers. Once the bar is in place the threaded insert can be reassembled in-situ. (I'm using a long threaded steel insert here, rather than simply threading the alloy, as this will resist wear better and reduce backlash in the thread).
 Bronze bearings used for the tilt-plate jacking bar. |
 Removable SS 1/2" x 13 tpi threaded insert. |
First, check that the bushes fit into the holes in the cast lugs on the tilt-plate, they should be a fairly close fit. Check again if any spacers are required, there should be about 1/16" total lateral movement allowed. If one or other bush won't quite go in the hole in the lug (because these holes are die-cast they aren't any exact size) then it will be necessary to relieve the holes a little with some emery cloth. When you're happy that everything fits you can assemble the bar and bushes in place, use a little Araldite to secure just one of the bushes in it's bore, then pass the bar through the opposite hole followed by the remaining bush. As before, smear the steel stub axles with a little grease as a safety precaution before cementing in place. Allow the Epoxy time to set before doing any further assembly. Note: it is optional whether the second bush is left un-cemented, as to do so allows the assembly to be stripped down again. However, my advice would be to cement this bush in place also as this will facillitate more precise adjustments. Finally, replace the threaded insert and tighten the nuts (be careful not to over-tighten the fine threads).
Before you re-assemble the wedge you can fit the optional tilt-plate ledge (a simple supporting bar for the scope's drive base, it is a help when mounting the scope onto the wedge). You could also fit this later if you wish using a hand-drill to make the holes. Fitting the ledge requires that two holes be drilled in the tilt-plate and then tapped 5mm Metric Fine thread. Place the ledge on the bottom of the tilt-plate (see diagram for positioning, or use the edge of the scope's base as a reference) and mark the centers for the two holes from the centers of the slotted holes in the ledge. Drill these holes 4mm right through, then use a 5mm metric tap to thread the hole. Tip: be careful the drill-point does not wander from where you want the hole to be, use a smaller drill (say, 2 or 3mm) to start with as this has less tendency to wander off line in the magnesium alloy. The two supplied 5mm cap-head screws can then be used to hold the ledge in place.
If you haven't already, insert and tighten all 4 side-plate bolts for each side. Locate the azimuth all-thread and put one set of thrust bearings on (that is, 2 bearing seats with the roller bearing between), insert the all-thread through one side and screw on the new azimuth dog - keep turning until the dog is roughly in the center of the all-thread and the end pops out through the hole on the opposite side. It will help if the all-thread is lubricated with some molybdenum-based grease. Put the second set of bearings onto the other end followed by a locknut, then the knob, and finally the acorn nut. It *may* be necessary, if there is not quite enough thread to get the acorn nut on, to loosen the opposite acorn nut a couple of turns (this might be a bit awkward as this is the nut that remained fast - remove the all-thread again and grip it in a vice between two strips of wood to prevent damaging the thread). When you are pre-loading the bearings with the locknuts you must be very careful NOT to over-tighten the bearings or you will destroy them. There should be no slack evident but the all-thread should be able to turn freely.
Place the brass slip-plate on the tripod (lubricate it both sides with a little grease), then put the wedge on top of ensuring that the two pins of the azimuth dog engage the slot in the tangent arm. Line up the holes and then use the 3 T-bolts to hold it in place. Loosen the 2 grubscrews on the dog and lower the extension until it rests on top of the arm, twist the extension such that all lateral play is taken up and then tighten the 2 grubscrews securely. Again, it's wise to lubricate the slot with a little grease.
Assemble the 2 sets of bearings and conical bearing seats on the fixed jacking bar and then insert the altitude all-thread through them. Run the two locking nuts up to the bearings and pre-load them to remove any slack. As with the azimuth bearings, do NOT over-tighten. Place the tilt-plate in position and insert thin (1/32") spacer between the tilt-plate and wedge side-plates on each side. Push the pivot T-bolts through both the side-plates and spacers and tighten them up. Thread the end of the azimuth all-thread into the threaded insert in the tilt-plate jacking bar, moving it to the approximate latitude. As mentioned earlier I recommend not replacing the latitude marker as it's not accurate enough to be useful, and the polar alignment routine takes care of the latitude adjustment anyway. Insert the four tilt-plate clamping bolts, one long and one short on each side (the 'T' bars will overlap). Without tightening them check the clearance between the side of the tilt-plate and the side-plates at the point where the T-bolts go in. If the gap is more than 1/16" then you will need to insert a spacer between them (the bronze ones with a 3/8" bore), hopefully this will not be necessary though. When making adjustments during alignment it will probably be necessary to loosen these T-bolts a little to prevent jerky movement - they clamp the tilt-plate up very tight!
Fitting the Optional Eyepiece Rack:
If you elected to purchase the optional eyepiece rack then this can be fitted to the assembled wedge. It's a bit fiddly to fit as the clearances are tight (I will try to modify the design to make fitting easier). In a workshop-modified job, this part would be fitted by drilling through the wedge side-plates and tapping straight into the rack. Most folk will not want to do this at home however because drilling the holes intot he edges of the rack is not easy. For the kit version I've added a couple of clamp brackets which grip the side-plates. To fit, you will need to take off both clamp brackets first and then slide the hole-plate into place through the gaps in the wedge side-plates. You can then re-attach the brackets using the two Allen cap-head screws on each side (believe me - it *does* fit, it's just a bit fiddly!). With both brackets on you can lift the plate upwards and secure it into position using the two grubscrews on each side (have the tilt-plate T-bolts loose while you do this). The rack is made from 1/2" alloy plate and adds substantially to the rigidity of the wedge.
Final Adjustments:
With the wedge mounted on the tripod, and the scope secured to the wedge, you can test whether the wedge performs as it should. You can tension the 3 T-bolts holding the wedge to the tripod fairly tight and still retain smooth movement - these should not require touching again unless you routinely remove the wedge. I leave my wedge permanently attached to the tripod - and transport it that way as a single unit. Check that the movement in response to turning the Az adjuster is smooth for it's full travel with no binding anywhere. There should be no backlash evident at this stage. Do the same for the Alt adjuster - but you need only check movement a few degrees either side of your lattitude setting.
It's at night, during a polar alignment routine, that you'll really test the wedge. Go through the usual polar-alignment routine, and whilst making fine adjustments to the wedge check for orthagonal movement using a reasonably high power reticle eyepiece (the 9mm Meade is good). Put polaris in the center cross, then use the Az adjuster to move the star to the edge of the FOV. Turn the eyepiece so the star lies on one of the lines. Now, when you turn the azimuth adjuster back and forth the star should track along the line. Similarly, using the Alt adjuster the star should track up and down the other line. You should also be able to make very small adjustments consistently (using a barlow to increase the magnification), and this feature is essential to obtaining accurate polar alignment. These are good 'before and after' tests to measure the improved precision of adjustment.
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