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30th Mar 2012, 12:52 PM #1Senior Member
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Another Problem with my Hafco HM-46 Mill Drill
So my HM-46 Mill/Drill has another issue!
First issue still not resolved is the mystery "clunk" when adjusting the quill or using the lever arm.
No solution to that I just have to work around the "clunk zone".
But another problem has surfaced!
Gearbox is leaking oil
On the plus side it keeps the vice and bed nicely oiled but that's hardly the point.
I assume a seal has failed and that means pulling it apart.
Machine hasn't really done a lot of work at all. Very dissapointed.
Cheers
Justin
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30th Mar 2012, 05:30 PM #2Most Valued Member
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Hi Justin,
This would be a real disappointment but don't feel too bad. If you totally take it apart to find the leak , then you will most likely be glad you did! Unless you scored an absolute gem then you will find that it is absolutely filthy with grim and casting sand/remnants from the foundry process.
So a thoughough strip down and clean will do it no harm! Finding the leak should not be a problem, first see if the drain plug is tight. That lives up under the head on the left hand side. Other issue maybe the seal at the top of the spindle, it may have been pinched or damaged when assembled. The other issue maybe where the electrical control box/switch box attaches to the head. Not sure about the HM mills but with mine, the electrical box that has the buttons attaches to the head with small screws, if they are not attached properly or tight then oil can leak out through the threaded holes. Only other place it can leak would be if there was a crack in the casting...... Lets just assume it's not that!
As for the clunk, You're not on your Pat Malone there either! Not sure how much investigating you have done but it may be the backlash in the rack/pinion and the quill may just be falling by a fraction of a mm each time the backlash takes up. There are a number of different remedies for that ranging from very easy to some quite elaborate engineering fixes that can be employed. Placing a tension spring between the quill and the mill head is probably the easiest and cheapest fix, it holds the quill hard up against the rack, removing the backlash on downward movements.
I hope I have not told you how to suck eggs. I'm very green on such matters and still learning most days!
good luck!
Simon
Ive since done a search of your previous posts only to find that you have already been through all what I have listed! Sorry!
Oh well, good luck with the leak. I'm sure it will be easier to fix than the backlash!
Cheers,
Simon
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30th Mar 2012, 06:53 PM #3
I put copius amounts of thick oil on the spline at the top where the( bar slides through to hold the chuck) cant think of its name. And that stoped my clunk
Kim
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30th Mar 2012, 07:40 PM #4Senior Member
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Yes the back lash. I prefer to call it a mystery clunk!
Nah you not telling me how to suck eggs at all.
After your comments it might be a good idea to pull it all down.
And on that note I'm going to ring Hare and Forbes and get me that pinion shaft and see if that helps.
What bugs me the most though is tha H&F have told be straight to my face they never have problems with these machines and what I'm describing is totally unheard of.
The other classic is; "Sir your expectations are too high you have to remember it's a mill/drill not a real mill"
Cheers
Justin
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30th Mar 2012, 08:12 PM #5Most Valued Member
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Anyone who has done a bit of research into these machines would know that they are not the very best money can buy. No surprises there but if you look at the H&F web site they say this about the HM46:
The usual handle-driven down feed is available for precision drilling and there is a fine manual down-feed control for precise vertical milling.
So, it's OK for them to say that it's not that accurate but not after they make these claims of their product in their sales pitch!
As for them not having any problems with the machine, well you and I know that this is simply a myth. They must think that you came down in the last shower!
There are several things that I'm not happy with on my mill but I just have not had any time to attempt a remedy. The way I see it is this:
As much as I would have loved to buy a machine and be extremely happy with it out of the box, the simple reality is that it's rarely possible with these machines unless you are not really into fine workmanship. So, I see it as more of a project machine and look at it as a challenge to improve it way beyond what the manufacturer ever anticipated. In doing so, I will learn a lot and gain much experience along the way in the art of machining. Doing a bit of research and looking at what others have done is also an enjoyable way of learning too.
The biggest issue is knowing you limits, keeping within them so that you don't stuff up an existing part and ruin the machine or degrade it's performance even further!
Cheers,
Simon
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30th Mar 2012, 08:29 PM #6Senior Member
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All good points I need to look at it as a "project".
Thankfully the majority of other functions work at least as expected or quite well.
It's accuracy is adequate for what I want to do.
They offered to swap my machine for another one but I knew that would only be swapping one set of problems for another.
Might be worth rebuilding it actually a good mate can get the cast iron casing impregnated with a Loctite product.
Cheers
Justin
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1st Apr 2012, 02:14 PM #7Senior Member
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I have been thinking. Possibly highly dangerous.
Now that I most likely have to rebuild the head on my mill I'm thinking it might be time to blue print the whole machine.
I might have access to a tool room and the people with the necessary skills all for a reasonable price.
I could get the rack checked and re machined if necessary and a new pinion shaft made up from scratch. Could then get the rack and pinion shaft properly aligned too.
Not something I would normally consider but if it has to be pulled down might as well put it back together better than how it came from the factory.
Or am I a bit nuts?
Cheers
Justin
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1st Apr 2012, 04:50 PM #8Philomath in training
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Justin, it's a nice thought, but I'd save the favours for a machine that is worth it. At the end of the day it's still a Hafco HM-46. No one will believe you if you get it down to tenth accuracy, and if you sold it you'd never get more than the price of a new one, so there is limited value in spending resources and time blue printing. While it is worth fixing up the bits that don't work and sorting the irritating bits out, making it perfect is overkill. Part of the fun of doing this home metal working thing is working out how to get around the problems with your equipment.
If you do decide to rebuild some parts of it remember to post some pictures so that those who come after you can do the same thing if necessary.
My thoughts
Michael
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1st Apr 2012, 07:26 PM #9Senior Member
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Stop all this realistic reality talk!
In the words of Adam Savage: "I reject your reality and substitute my own."
But seriously I'm mainly concerned about the rack and pinion. If I can get the clunk out of it I'll be more than happy with the machine.
Problem with the clunk is it's in the first 10mm of travel right in the range where you are meant to opearate the machine. It drops about 1mm.
Cheers
Justin
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1st Apr 2012, 08:15 PM #10Most Valued Member
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Does it particularly matter if you use the machine with the quill extended by more than 10mm,I think they have a range of around 120mm.
Have you performed any tests with the quill lock nipped to see if there is a reduction in the amount of drop over the same distance.
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1st Apr 2012, 08:20 PM #11Most Valued Member
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What he said!
Like i said previously, i have a list of things i would love to do to my mill and lathe but i also find it easy to get out of control and i think its important not to over capitalize on these machines to the point where you may as well have just bought a better machine to start with. My approach is this, i will consider a mod as long as it can be done with my time, my skills and in my shed.
I would spend a fair amount of time investigating and measuring to find exactly what's wrong. Others on this forum have spoken about similar issues with the quill (im in the same boat) Dave j has mentioned about an eccentric bush on the pinion that will allow you to bring it closer to the rack. This is one treatment that may help but you need to strip it down to find where the issue is. I plan on using a tension spring from the quill to the mill head and installing a dro on the quill to get around the issue. Both of which i have, sitting and waiting to be installed!
Cheers.
Simon
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1st Apr 2012, 08:49 PM #12Senior Member
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I have spent hours and hours and hours on the quill and all I can determine with any degree of confidence is it's "something" to do with the rack and pinion. My suspicion is that the rack and pinion don't mesh properly the teeth are to loaded Incorrectly/inconstantly.
I have tried every trick in the book to get around it.
For the most part I operate outside the clunk zone and use a mini dial indicator to measure how far the quill actually moves.
There is some run out on the pinion gear shaft. Hard to tell if that makes a difference.
Having access to the gear to fix it properly is an option and I know what people are saying but if I can fix the quill issue the machine will certainly be more than good enough.
Might add we have tried numerous pre-load techniques but still no good.
I'm thinking of getting the rack checked thoroughly might even bearing blue it and then see the contact profile. I suspect a new pinion shaft and line boring the location points might just do it.
On a side note my lathe is a Compact 8 made in Austria and it's brilliant!
Cheers
Justin
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1st Apr 2012, 09:20 PM #13Most Valued Member
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Whatever you decide, good luck. Please keep me/us posted as i for one have a keen interest in your findings and the results.
Cheers.
Simon
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9th Apr 2012, 08:09 PM #14Senior Member
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Bit of an update.
Oil leak found!
It's one of the selector shafts, the lower one of course.
I popped the seal out and you can see quite a lot of oil weeping out.
Not 100% sure if the seal failed per-se or it's just a stupid design where the oil builds up behind the seal and then seeps past. No real wear on the shaft what so ever. Not even a rub mark.
Will put in a new seal and see how long that lasts for really not sure about a long term solution.
With the seal removed you can actually watch the oil seep out past the selector shaft.
Open for any ideas!
Cheers
Justin
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10th Apr 2012, 11:50 AM #15Senior Member
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New seal installed today.
The recess that holds the seal is not properly round and getting the seal to sit in squarely was quite difficult.
Stuffed the first seal in the process, lucky I bought 2 seals!
Super extra careful pushing in the second seal to get it as square possible. I've topped up the oil and will wait and see now.
Wondering if I should try a heavier weight oil.
Cheers
Justin
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