The aluminium tripods that come with a majority of beginner and mid-range scopes have had a bad name for years as being poorly made, sloppy and people have tried various ways to make them sturdier such as filling the legs with sand, lead shot, or even expanding foam. 
I just read an account the other day of where a person was fitting steel rebar into the legs to see if it will help…
The only problem with these solutions is that you end up with a very heavy cumbersome tripod that is really no better than what it was when the modifications were started. 
I will show you what I do with these to help take the shakes out of them. 
The tripod modifications can be done to any of these aluminium tripods and not limited to adapting the SLT mount.

Before starting the modifications, read the instructions thoroughly! If there is any part you are not sure of feel free to PM me.

The tripods are manufactured cheaply and are not a precision work of art but can be fixed to be quite usable for only a few dollars.
There are 3 different pivot points on the tripod that total 21 different places that the tripod can move so these can all be stiffened up.

Tools required:
Robertson or Phillips screwdriver
Drill and ¼” and 1/8” drill bits
Skilsaw
Hacksaw or angle grinder
Fine flat file
White glue
Paint or varnish of choice
Socket/ combination wrench if using nylocks

All the needed supplies should be available at a local hardware store. 
18- #6 flat washers
18- #8 x 3/8” sheet metal screws
3- 1/4” x 3 1/2” bolts
3- 1/4” wing nuts or nylock nuts (preference)
6- 1/4” x 1” flat washers
6- 3/16” x 1” bolts
6- 3/16” wing nuts or nylock nuts
12- 3/16” x ¾ or 1” flat washers 
1- 1/8” x ¾” aluminium flat bar (need about 9”)
Container for all the old bolts and screws

Note: If you wish to paint your tripod and mount I recommend a degreaser and an aluminium etching primer to help the paint adhere to the aluminium parts. 

For this I will show what I did to adapt the aluminium tripod to a Celestron SLT hub/mount.

The supplied screws/ bolts holding everything together are cheaply made and it does not take much to strip these so all the hardware will be replaced with better quality. 

Start by taking the tripod legs off of the hub and set the hub aside as it will not be reused. 
Take the legs apart and remove all the factory screws/ bolts holding the cast metal pieces together. 
Check all of the plastic end pieces in the legs to make sure they are tight. 
If not they will need to be removed for now. You may wish to mark all the pieces so they go back together on the same leg but it is not essential. 

If you are going to paint your tripod/ mount now is the time to do it and give it a full day or two to properly dry. 
Use either #220 grit sandpaper or a course scotchbrite pad to scuff the metal to help it adhere to the parts. 
Do not forget to scuff the primer before painting! 

Now that you are ready to put the tripod back together we will stiffen up any of the plastic leg inserts if they were loose. 
The only piece you do not want to do this to is the top cap for the center leg. 
Do not install this cap or the center tray support brackets at this time. 

Put a bead of white glue around the inside of the leg where the insert goes and then push the insert into place. Using the new #8 x 3/8” (6 per leg set) screws, snug all the parts up. 

Picture 1:
 

Set aside and let the glue harden.
The #8 screws are slightly larger than the original size and will snug up nicely. You can see the difference in the photo above.

I tend to reuse the lower single leg bolts as they are usually fine for this job. I use the glue on the insert and then the bolt.

Before you reinstall the cast lower leg pieces run your finger around the hole that the center leg slides through, if there are any rough or sharp spots file them down smooth. 

Now that everything is dry start reassembly by installing the side legs and then slide the center leg up through the bottom. 
Set the legs aside for now. 

Now we get to the fun part, power tools!

Using the 1/4” drill bit enlarge the holes on the SLT mount hub to match the larger hole in the tripod legs. Once done set this part aside. 

The next step is modifying the center tray supports.
The supplied tripod tray is a flimsy piece of stamped metal and using the 3 original screws and wing nuts leaves much to be desired for tripod stability!
Using 6 bolts in the tray will hold the legs firmly in place and not allow any play.

Using the drill and the ¼” drill bit, drill a hole at the furthest end of the slot and another half the distance of the support. 

Picture 2:
 

Now to make the new center tray. This tray will spread the legs out a bit more making alarger ground triangle which helps with stability. 
I used a piece of 3/8” plywood with dimensions of 15 3/4” on the flat side and 13 5/8” flat to peak. Your 2 holes should be approximately 2 ½” and 5” from the peak. 
Drill ¼” holes and set aside for now.

TIP: Use the tray support as a template to mark out the holes to ensure alignment.

Picture 3:
 

Using the aluminium flat bar cut 3 pieces 2 3/4” long. Use the file to smooth and round off the edges of the piece. (I used the edge of a quarter as a template to round off the corners.)

Now to reassemble the tripod! 

Take a leg assembly and lay it flat on your work surface, insert the center leg cap at this time but do not screw it into place. 
Take one of the flat bar pieces and lay it across the legs butted up against the lip of the center cap and mark out the location of the screw hole on the flatbar. 
Using the 1/8” drill bit make a hole and then install this with the center cap.
If you have ever noticed on these tripods, as soon as you put some weight on them the center leg tends to slide/ lean inwards which causes only a small part of the leg to actually be making full contact. This flatbar brace will keep the center leg inline with the other legs when the scope is mounted. 

Picture 4:
 

Optional: I drill a second hole and rivet it into place so that the flatbar cannot loosen off and the cap can still be unscrewed and removed if needed. (3/16” drill bit and 1/8” rivet)

Once the flatbar is attached turn the leg section over and it is time to install the tray brace. 
Screw one of the pin brackets onto the leg and then insert the pin. 
Put 3 of the #6 flat washers on the pin and then slide the tray bracket on (flat side up). Install 3 more #6 flat washers and then the other pin bracket. Screw bracket into place. 
The tray support bracket should be nice and snug between the brackets now and there will be no slop for it to slide around on the pin. 
Repeat for other legs. 

Picture 5:
 

So now the tripod should almost be done, take the mount hub and install the new 1/4” x 3 1/2” bolt.
At a minimum you should have a flat washer under the bolt head and one under the wing nut.
Check the gaps between the legs and hub to make sure they are in full contact with each other. 
If there are gaps between the legs and hub use 1 or 2 appropriate thickness washers to fill the gap.
Plastic report covers can be cut to make washers if the gap is small.
You want the legs parallel but not squeezed to the point you cannot adjust the center leg smoothly.
Use a 1/4” x 1” flat washer and then your choice of either a wing nut or nylock to tighten things up.

Tighten until the leg is stiff but can swing without fighting it. 
Repeat for the other legs. 
You should now have a complete tripod minus the tray. 

Final step is to install the tripod tray using 2- 3/16” x 1” bolts and 4 flat washers for each leg. 
I use one washer on top of the tray and one underneath the bracket so you can tighten these up very well with the wing nuts or nylocks. 

Picture 6:
 

You should now be the proud owner of a very stiff aluminium tripod that no longer has a bad case of slop/ shakes when you put your scope on it.