10 x 18" (250x450mm) Bench Lathe
some modifications I did to my CQ9325 metal lathe which should have
been included in the
Belt drive tensioner
The lathe definitely needs an adjustable tensioner for the intermediate pulley.
This is easily made up.
A centre bored steel block is machined to fit between the rear of the intermediate pulley and the cast iron pivot plate.
spindle for the intermediate pulley passes through this.
A threaded adjuster shaft passes vertically through the left side of the steel block, running parallel to the centre line of the two pulleys (green arrow).
The bottom end of the adjuster shaft (a load bearing free pivot point) is located in an open retainer attached to the left pair of motor mount bolts (red arrow).
the shaft raises
the steel block
(via the threaded section) to lift the intermediate pulley spindle, and
tension the vertical belt.
The free floating steel block is kept away from the rear of the intermediate pulley by a circlip in a groove, machined into the intermediate pulley spindle - see below.
This is my number one modification for this lathe.
slide freeplay adjuster
This is easily fixed by slotting down through the brass block at the oil port hole, and adding two 5 mm diameter adjusting bolts. A similar system is used on larger lathes.
Original block seen below.
Modified adjustable block seen in next photo.
The HBM450 (CQ9325A) sold in Europe has this style of adjustment block fitted as standard.
I simply copied that.
Drill and tap the two bolt holes and you're done.
I also added a spring washer to each bolt.
Adjust the freeplay with the shaft removed as it's inaccessable when fitted in place.Carriage handwheel fix
The system basically distorts the block slightly by canting the smaller section inwards, applying tension to the thread.
It works very well. No more backlash.
This will get rid of the wobble and have it turning silky smooth.
Drop the lowest spindle speed by 50%
At 125 RPM the slowest speed is too fast for some jobs.
Here's a modification I did to slow things down.
Correct the longitudinal feed speed
By changing the 34 tooth gear (Z2) to a 30, the feed rates listed in the user manual are achieved.
This may have been the original intent, as the gears supplied/fitted do not give a true two decimal point low feed rate - which is unusual. Something got confused along the way.
You can see the correct gear positioning below.
If a 30 tooth gear is not available locally, an enquirey to an on-line store selling this model lathe may enable you to source one from their spare parts service at a reasonable cost.
Alternatively you could make one.
Click here to see how I easily made replacement change gears on this lathe.
Longer cam lock lever and stop
The original lever is way too short.
I lengthened the cam lock lever and added a lever stop to the tailstock - similar to one I saw on a CZ lathe.
The 6 mm metal pin prevents the lever from dropping down when unlocked.
The stop is threaded into the tailstock and has a screw slot in the end.
Both are easy modifications.
Lock nut for the cam lock bolt
The original plain nut loses it's adjustment position. Replace it with a nylon collar type lock nut.
Locating bush for the cam lock bolt
I added an internal bush to the tailstock cavity, to help locate the camlock bolt in the vertical position.
This prevents the tailstock retainer block from canting and binding on the ways when using the tailstock partially unlocked - eg. when manual threading into the headstock.
It's simply a bush and locating flange (seen out of the tailstock cavity here) with a spring to hold it in position.
Used in conjunction with the camlock lever stop, it allows you to set light tension on the cam bolt with the tensioning nut.
Additional tool post mounting position
Simple modification to reposition the compound mount on the cross slide - for close in work.
See here for details.
Cross slide lock
For some jobs it's very handy to be able to lock the cross slide - eliminate backlash.
This will greatly reduce the instance of harmonics or movement affecting work finish when grinding, milling and turning.
I looked at designs on the web and didn't like any of them. They were either bulky, complicated, likely to upset alignment, got in the way, or not terribly effective looking.
So I came up with the following simple lock.
The red arrow indicates the Allen head of a 6 mm bolt which applies pressure to the side of the gib blade.
Simply drill and tap the cross slide, slightly recess the end of a bolt, put a small ball bearing down the drilled and tapped hole, and screw in the bolt.
What could be easier?
Works brilliantly with very light tension. Won't upset the gib adjusters.
I have seen people replace an existing gib screw with a heavier bolt as an alternative.
This isn't a terribly good idea as you have to re-adjusted the bolt each time after use, to prevent variable alignment and possible uneven wear in the cross slide dovetails.