Looking for aluminum machining to be done


Greg Anthony


I'm looking to get some parts for my motorcycle modified. The first 2 pictures are of the part that needs the modifications and the second 2 are of what the final part needs to be similar to. I would need two of these done. The small ridge shown in the first picture needs to be flush to the existing surface around the hole and the hole needs to be enlarged (from 15mm to 22mm approx.)





Here is a picture of what the complete part looks like.


The measurements of the piece are as follows (all approximate):

Overall height: 185mm
Height of main part: 140mm
Distance down to hole - from bottom (The square end): 60mm
Distance down to hole - from top: 75mm
Diameter of opening in bottom: 28mm
Diameter of opening in top: 43mm

The part is cast aluminum.

I can also reinstall the fork tube if needed to provide a place to hold


My email is gregant1111 at gmail.com if you need more info or to discuss further.



Greg Anthony

I should have stated in my original post that I am located in Sherwood Park and am looking for someone local to the Edmonton area to perform this work.

John Conroy

Premium Member
Are you in a hurry to get this done Greg? I could certainly do it for you but probably not for a week or 2. I live in St. Albert.


Jack of all trades -- Master of none
Premium Member
What is the context of your mod? Why are you changing it and what is the objective?

It may yield some alternative ideas/solutions

Lots of us are also motorbike enthusiasts.

Sent from my iPad using Tapatalk

Greg Anthony

New Member
I have spoken with John and he thinks he will be able to do what I want done.

These parts are Showa fork lower stanchions from a Ducati Monster S4. I am trying to install the damping rod and valves from a Ducati 999 fork into the S4 forks because the 999 fork internals are a better design. The external dimensions of the upper fork tubes are different so the 999 forks will not bolt up directly to my bike (a Ducati GT1000) but the S4 forks will. The way people typically do this modification is to machine out the fork tube holes in the top of the triple tree so the complete 999 forks will fit but I didn't want to do it that way as I was concerned about the strength of the top triple after enlarging the fork holes, the lower fork tubes on the 999 forks are not in the best condition and the fender mounting points are different.

Since I had both sets of forks, I disassembled them and realized that if I enlarged the bottom hole in the fork stanchion to fit the compression adjuster bolt for the 999 fork damper I could just install the 999 fork internals into the S4 forks. The diameter is larger because the entire compression valve/adjuster assembly is installed through this hole. On the S4 fork, only the adjuster goes through the hole as the compression valve is non-replaceable and is pinned into the end of the damping tube.

John Conroy

Premium Member
Greg dropped off the fork parts yesterday evening. The large bore need to be enlarge by only .012" and the bottom of it needed to be flat. The small bore needed to be opened up by about 1/4". Luckily Greg had a scrap fork tube to thread into the stanchions so they could be held accurately in the lathe chuck. The OD of the tube is 43 mm so too big to fit into the lathe spindle so I had to cut it to the minimum length that allowed that. I used a 3/8" boring ba with a dcmt carbide insert for both the boring and facing of the bottom of the bore. After chucking the part I had a hard time figuring out how to verify run out since I don't have a DTI with a stem 2.5 inches long. I had to make up an adapter so I could attach my old Starrett last word indicator as it is small enough to fit into the 1-1/16" bore. Both had less than .001" run out when in the chuck.












Ultra Member
Premium Member
Nice work on both the fixturing & measuring, John. Looks to be the typical machinist 80/20 rule - 80% getting it set up & held properly, 20% on the actual cutting operation.


Lee - metalworking novice
Premium Member
Thanks for the pictures, I was not following well till I saw the pictures. Not being a bike does not help the situation. Great job.