Ideas to fix pilar drill

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jb94

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Hi,

Sadly the depth stop on my Clark drill press has broken off!

It appears that only a thin bit of plastic was holding the threaded rod onto the housing.

Wondering if anyone has some bright ideas on how to fix it, hopefully an idea that would last not just a quick fix

I could reuse the threaded rod and put a bolt above and below the red housing, but I’d loose a lot of rod height, alternatively I could make a new part somehow maybe from a section of 10mm threaded rod and cut down one end to fit the flag onto?

Cheers

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Depending on how much you want to spend or are prepared to get creative you could fit a digital read out (DRO). They can be had fairly cheaply from Chinese suppliers, or through https://www.arceurotrade.co.uk/Cata..._DNNn7ChrOuZEOv6iSi83-3FYQo2RliBoC6KcQAvD_BwE

Alternatively if you can make a couple of simple brackets you cannibalise a cheap Vernier caliper to make one, although the read out will be at 90° to where you want it
 
Replace the red plastic with plywood.

Drill a 4mm tapping size hole for what looks to be an M5 thread and screw threaded rod into plywood using the pair of locknuts to provide traction. Once threads are formed, remove rod and squirt superglue around to reinforce the threads. Insert the rod again and add more superglue in the joint to lock the rod into the ply.

Buy some 2-part epoxy putty and bung up the original hole in the plastic. Form a flange on the top and bottom so the glob of putty cannot come out of the hole. Wax or oil the threaded rod and screw it in when the putty starts to harden.
 
Depending on how much you want to spend or are prepared to get creative you could fit a digital read out (DRO). They can be had fairly cheaply from Chinese suppliers, or through https://www.arceurotrade.co.uk/Cata..._DNNn7ChrOuZEOv6iSi83-3FYQo2RliBoC6KcQAvD_BwE

Alternatively if you can make a couple of simple brackets you cannibalise a cheap Vernier caliper to make one, although the read out will be at 90° to where you want it
Thanks for the suggestion.
I don’t want to spend too much money on fixing as eventually this drill will want changing to something better.
 
Replace the red plastic with plywood.

Drill a 4mm tapping size hole for what looks to be an M5 thread and screw threaded rod into plywood using the pair of locknuts to provide traction. Once threads are formed, remove rod and squirt superglue around to reinforce the threads. Insert the rod again and add more superglue in the joint to lock the rod into the ply.

Buy some 2-part epoxy putty and bung up the original hole in the plastic. Form a flange on the top and bottom so the glob of putty cannot come out of the hole. Wax or oil the threaded rod and screw it in when the putty starts to harden.
Thanks I’ll give the Milliput idea a go and if that doesn’t work make a new part from plywood
 
Amazingly complicated solutions being offered here. Use one of these, you just need to know what size the thread on the end of the rod is.
Commonly sold as cabinet joiners, in various metric sizes. Drill the plastic bracket to suit the OD of the fitting, cut the fitting down to a suitable length, most are threaded a good way down.
Alternatively use a suitable sized rivnut and just glue it in.
 

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How about this ?
With a piece of hex bar (8 or 10mm ?), glued and pinned into the
red plastic, then the sliding collar used to set the depth and locked
with the screw.
Heavens...!! You could even graduate the hex bar (y)

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Good idea. If you regularly use particular settings you could drill shallow holes in the bar to accept the end of the screw for easy adjustment. Or just attach the existing flag and use the scale. You could just as easily use round bar, that would slide better in the guide hole. Good idea to use a brass screw so it doesn't chew up the surface of the rod.
 
Use one of these, you just need to know what size the thread on the end of the rod is. Drill the plastic bracket to suit the OD of the fitting,

I think you are looking at different photos from the OP to the ones I am seeing.

In the ones I see, the lower thread of the rod appears to measure 5mm.

Again, in the photos I can see, the red plastic has a hexagon-shaped hole in it suitable for a (presumed M5) nut, which would have a larger A/F dimension than the shank of the barrel nut.

How do you switch off gravity and stop the barrel nut falling downwards through the hole, dragging the rod with it?

If you regularly use particular settings you could drill shallow holes in the bar to accept the end of the screw for easy adjustment.

Please think about what you are saying here. The setting of the depth stop depends on the length of the drill bit in the chuck, the thickness of the material and the position the table is clamped to the column.

If any of those change, the shallow hole in the bar will no longer be correct. What is more difficult, re-setting the table to the exact same place on the column or adjusting the depth stop?

---

The sliding, lockable collar relies on the friction of the locking screw to maintain its position. If you are at all heavy-handed on the quill (and because it is a rack and pinion, you have a lot of mechanical advantage) it will be easy to make the collar slide up the rod, screwing up your depth.

There is a reasonable chance that the original has broken for this same reason: pull down too hard on the quill handle, the depth stop bottoms out and puts strain on the rod-plastic joint.

It is OK to put the fiducial marker on a sliding, lockable coallar but the depth stop proper benefits from a positive locking mechanism.
 
Working on the assumption that the plastic is still strong enough to hold, if you still and tap a hole through the bottom of the threaded rod, screw it into a captured nut in the hex hole. Then screw a washered bolt from underneath into the new threaded hole until tight. This should let you keep the full length of the original rod.
1000031787.jpg
 
I think you are looking at different photos from the OP to the ones I am seeing.

In the ones I see, the lower thread of the rod appears to measure 5mm.

Again, in the photos I can see, the red plastic has a hexagon-shaped hole in it suitable for a (presumed M5) nut, which would have a larger A/F dimension than the shank of the barrel nut.

How do you switch off gravity and stop the barrel nut falling downwards through the hole, dragging the rod with it?



Please think about what you are saying here. The setting of the depth stop depends on the length of the drill bit in the chuck, the thickness of the material and the position the table is clamped to the column.

If any of those change, the shallow hole in the bar will no longer be correct. What is more difficult, re-setting the table to the exact same place on the column or adjusting the depth stop?

---

The sliding, lockable collar relies on the friction of the locking screw to maintain its position. If you are at all heavy-handed on the quill (and because it is a rack and pinion, you have a lot of mechanical advantage) it will be easy to make the collar slide up the rod, screwing up your depth.

There is a reasonable chance that the original has broken for this same reason: pull down too hard on the quill handle, the depth stop bottoms out and puts strain on the rod-plastic joint.

It is OK to put the fiducial marker on a sliding, lockable coallar but the depth stop proper benefits from a positive locking mechanism.
The main shaft of his depth stop is 10mm stepped down to M5 at the end. or maybe the larger diameter is 9mm from the image, which would be odd. Either way it using going to fall through the hex hole for the nut in the plastic, a regular M5 but being 8mm AF. So an M5 joiner screwed onto the end of the stop shaft from below and through the plastic part would hold it. Yes you might need to put a washer on it, depending on the size of the flange on the joiner versus the hole on the underside of the red plastic collar. Probably be a good idea to use a washer on the end of the stop shaft to span the hole left by the nut. Having the red plastic part sandwiched between the rod and fixings will make it stronger than the original fitting, and has the advantage of retaining the depth stop in it's original form.
So not really seeing your point.
As to the stop using a clamped fitting I agree an immovable stop is better in many ways, and yes probably heavy handed use is what has pulled the existing one apart.
So if I were to do something like this I would probably go for a more robust clamp.
You could of course argue that if too much force caused it to move it might encourage a lighter touch, and so lessen the likelihood of a repeat failure.
As to your final observation I would agree entirely for random use. If the OP regularly uses it for cutting numerous holes to a particular depth, then it could prove useful in knowing that a given setting results in, for example 25mm of travel.
It depends what he is doing and what tools he is using. It was a suggestion. It would be for him to determine if the idea has any merit in his particular circumstances.
As to set up I'm guessing you have never used a repetition lathe or similar, where a few minutes set up is well worth it to then repeat a process multiple times. As I say depends what he is intending to do with it, which neither of us knows.
 
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Working on the assumption that the plastic is still strong enough to hold, if you still and tap a hole through the bottom of the threaded rod, screw it into a captured nut in the hex hole. Then screw a washered bolt from underneath into the new threaded hole until tight. This should let you keep the full length of the original rod.View attachment 183005
The problem I see is that if the end thread is M5 then the core diameter is 4.2. So your screw would probably have to be M3 or thereabouts, not very strong.
 
If I were going to do this repair I would retain the original depth stop.
I would first drill out the hole in the plastic collar to 8mm. Then I would take a piece of say 13mm AF hexagonal bar and turn a sleeve nut with a 13mm AF head and an 8mm shaft through threaded to suit the end of the bar, presumably M5. I would make the length of the shank 0.5mm less than the thickness of the plastic collar. I would then use a large OD washer on the end of the shaft to spread the load. I would screw the sleeve nut up from below so that the plastic collar was firmly clamped between the washer on the end of the shaft and the head of the nut. A simple solution, and much stronger than the original. I might even choose to simply replace the plastic collar with one made of aluminium or steel.
But I have hex bar, and aluminium and steel.plate in various sizes. I also have a lathe and milling machine. These things may not be available to the OP.
The use of a jointer type sleeve nut is a simple solution. It might need some washers to space things, depending on the size of the shaft and flange of the sleeve nut, but still an effective and simple solution.
 
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Update, the plastic drill collar is utter rubbish, the bolt hole just fatigued and cracked meaning if you applied a bit of pressure on the stop the bolt would pop out.

Because this is a cheap piece of Chinese junk it appears the chuck is not a MT and must be fixed - there’s no way to remove it.

The inside of the chuck has no locking screw - looks almost riveted, the pulley inside is not hollow so I can’t hit a bar down to knock it off and there’s no holes in the shaft to give leverage. There’s a lip which I’ve tried to pry apart but it’s bent a hefty flathead screwdriver and hitting it with a lump hammer and crowbar won’t shift it.

I had to snap off the red plastic part to remove it, I suspect it was put in place before the chuck was fixed.

I guess I’ll need to make a new 2-piece drill collar with 40mm hole to fit on the flange.
 

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Update 2.
I made a replacement part out plywood, but at the end of the travel at the depth stop, there’s a bit of flex in the ply such that it will give a few mm which isn’t great for accurately drilling hole depth.

Will probably need to make it out of metal to mitigate that.
 

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If you go to the Clarke website you can download the manual for it, there are loads and don't know your model. Looked at a couple and they have a taper fit chuck. You might need to get a wedge type tool to remove it, but it almost certainly does come off, never come across one of any make where the chuck cannot be removed, but they are often pretty stubborn.
I know the collar is not the greatest quality part, it looks very similar to the one on mine, which is a Wickes own branded one, and not particularly robust !
Have you looked at what they charge for a new one? The manuals generally have an exploded drawing with part numbers, so should be easy enough to find out if it is available and at what price.
 
Check e bay listing 325048465414. Generic part from Finland, 11 odd quid including delivery to UK. There are loads similar on the web, mostly in US. This is plastic there are also metal ones. Dare say if you look around there will be someone here selling them. Also available on Ali Express. Or maybe someone here could 3d print one?
 

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