Author Topic: Proxxon PD400  (Read 38977 times)

Offline wongster

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Proxxon PD400
« on: January 01, 2012, 01:35:52 AM »
Hello folks,

Blessed New Year to all!

I received the Proxxon PD400 lathe 3 days ago am am still getting myself familiar with it. This is a first time I have my hand on a lathe other than the Sherline.

I encounter the problem of handwheels being too stiff to turn. Loosening the screw holding the handwheels make it easier for the cross slide and compound slide though not as smooth as what I have on the Sherline. I tried adjusting the gib without much success. The carriage and leadscrew handwheels are still giving me problem.

Anyone with a similar lathe or the PD400 encountered this and found a solution? There are little resources available online and no user club. The manual that came with the lathe is rather skimpy.

I've updated my blog with some pics of the slides taken apart. They look quite similar to the mini lathe on some aspect.

Appreciate any help.

Regards,
Wong
www.wongstersproduction.blogspot.com
« Last Edit: January 06, 2012, 01:29:50 AM by spuddevans »

Offline Swarfing

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #1 on: January 01, 2012, 05:12:57 AM »
Wong

For a new lathe i do not see a single bit of lubricant or grease on your pictures. Are you sure it just not needs a good dose of grease and oil?
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Offline David Jupp

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #2 on: January 01, 2012, 05:51:53 AM »
I can't see the condition of the slides very well - on many machines these aren't prepared to a very good standard at all.  On my co-ordinate table I got a HUGE improvement in smoothness of travel by briefly lapping the slides with some lapping paste (making sure I cleaned up well afterwards). 

This did no more than remove the highest points of the (relatively roughly) machined surfaces - I didn't aim for a visibly smooth surface as I didn't want to risk losing correct alignment.  I wasn't confident my lapping would be uniform across the whole slide.

On higher cost machines, the slides would typically be scraped - this is just too costly in the production of budget machines.

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #3 on: January 01, 2012, 06:59:41 AM »
I put some grease on the dovetails and on the gibs. Pics taken after I did some cleaning up.

For the leadscrew handwheel, it turns smoothly with the 1/2 nut disengaged.

Offline grayone

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #4 on: January 01, 2012, 10:52:18 AM »
Hi Wong I have the very same lathe and as yet have not used it very much (being back overseas working again).  I must admit that the long travel was a bit "sticky" until I got it proprly cleaned.  I did not use grease just used engine oil, don't know if that is good or bad.  It is still not as smooth as I would like and will still need to work on it a bit.  What I have done but yet to use is bought some specific lubricant for the slideways.  What I would say is that if you are struggling an email to Proxxon in Germany will be answered by the technical group.

I have much of the attachments that you have bought (and a few more as well - my wife thinks I am a Proxxon collector or shareholder  :D).  I am curious about the problem with the ball turning device as I have that as well - have you managed to get it working yet?

Graham
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Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #5 on: January 01, 2012, 12:28:09 PM »
Hi Graham,

I just finished taking off the compound and cross slides to clean up again.  This time, I put plenty of grease on the necessary parts. The part that makes the turning of the handwheels smoother is the contact surface between the handwheel and the part of the slide that it comes in contact with. After much playing around with the tightness of the nut holding the handwheel, the compound and the cross slide can move much easily than before.

I also took out the leadscrew to give it a good amount of the way oil I bought from A2ZCNC while trying to remove the carriage.  It just got jammed at the end of the way. Couldn't figure out what's blocking its exit.  I saw that there is a plate beneath the carriage that is held by 2 capscrews. This, I think, act as the carriage lock. The locking is done using the 3rd capscrew that is accessible from the top of the carriage.  The other 2 can't be accessed unless I turn the lathe upside down; something I'm not willing to attempt given its weight.  The 2 capscrews may be a little tight to allow free movement.  I'm just suspecting as I'm an absolute newbie.

As the carriage handwheel and the leadscrew handwheel are both stiff to turn, I find it difficult to start on any project.  Found a work around though; use both the handwheels at the same time.  This works nicely and the movement along the ways is now smoother.  I'll be doing this for the time being till I've someone willing to come by to help me lift up the lathe from the chip tray and flip it around.

I've not done anything further on the radius attachment.  I think a longer piece of rod would be required to give enough clearance from the chuck.  I've some time tomorrow.  Will do some test and probably play with the radius attachment somemore.

Regards,
Wong

Offline grayone

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #6 on: January 01, 2012, 01:07:19 PM »
On higher cost machines, the slides would typically be scraped - this is just too costly in the production of budget machines.

Hi David

Just a comment from a point of view of expectations these are not budget machines and in the UK cost around £2,000 compared to a similar Asian 7 x 14 ones of round £500.  I suspect that a certain amount of bedding in may be required once the ways are cleaned and the gibs adjusted.

Wong you are quite correct the plate under the bed acts as a gib for the long travel so may need to be tweeked a bit.  Please keep in touch with how you are getting along as in the UK at least there are not many owners of this machine that I can find on the web.

Regards

Graham
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Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #7 on: January 01, 2012, 01:26:26 PM »
Sure do, Graham, and thank you for clarifying that I didn't pay more than 4 times the price to get a lathe that is still within the budget range. If it is, I would rather just buy the SIEG and save the rest for other stuff.

Regards,
Wong

Offline andyf

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #8 on: January 01, 2012, 06:46:05 PM »
Hi Wong,

You mentioned that the leadscrew handwheel was hard to turn, though it turned easily with the half-nuts disengaged.

With the half nuts disengaged, can you move the carriage easily with the handwheel on the apron? If not, I can think of two reasons:
1.  Looking at the picture of the cross slide dial in the right-hand column half way down this page, http://thehobbyistmachineshop.com/shop23.html , there are three black Allen bolts going down through the carriage. Only two will be needed to hold the apron in place, so the third (one of the two on the left) is probably a carriage lock. It may have been tightened up to lock the carriage before the lathe was shipped, so check that it is not still tight.
2. The gibs on the carriage need loosening up a bit.

If you can run the carriage along easily with the apron handwheel, it is possible that the half nuts are not properly aligned to the leadscrew. In that case, the leadscrew handwheel should be easier to turn when the carriage is mid-way along the bed than when it is at either end. Midway, the leadscrew can bend to accommodate the misalignment, but near the ends it can't bend so easily. Put the carriage mid-way, and watch the leadscrew for any horizontal or vertical deflection as you engage the half nuts. If the deflection is horizontal, there's sometimes a bit of wriggle room on the two Allen bolts which hold the apron in place. Move the carriage to one end or the other, loosen the bolts, apply the half nuts and then tighten the bolts up again.  If the leadscrew deflects vertically, a fix may be more complicated.

Andy

Edit: The author in the link I gave above says "Every axis has a lock". Could it be that the cross-slide and compound were also locked up for shipping?
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline Miner

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #9 on: January 01, 2012, 09:45:10 PM »
You really should be using a proper way oil. It also helps to flush out chips etc. Grease will retain that contamination. Your slides will also work much smoother with a proper way oil. That's a fine and high quality lathe. It would be a shame to wear it out faster than nessisary.

Pete

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #10 on: January 01, 2012, 10:42:49 PM »
Hi Andy,

Yes sir, all axes lock were loosed.  They're done via this tiny capscrews which I wonder if they're at all effective in locking up the axes.

I was over at Dan Kautz' site for many times before deciding on the lathe. The excitement of having the lathe makes me forgotten to check back on some of the photos and comments he made.  Thanks for pointing me back.

I went through the manual again late last night (or rather this morning at 3am). Nothing mentioned about the 3 bolts on the front of the apron but a diagram pointed out that the "clamping screw" for the carriage is on the saddle between the ways.  In the section that covers adjustments of "guide play", it shows that the adjustments are via the 2 sets of studs and screws on the gib plate underneath.  So flipping the machine over is inevitable if the gib plate is the culprit for stiff movement of the axis.  Let's hope it is not at this point but I'll keep it in mind.

The leadscrew was observed for any movement when the half nut was engaged and disengaged.  Saw some vertical movements.  When engaged, the leadscrew was lifted up quite a bit.

I'm trying to remove the carriage from the ways but it seems stuck at the end of the way.  Wanted to see how the carriage works and if there is anything I can further adjust for smooth turning.  The closest I can find is the article on mini-lathe.com.  The article mentioned that the carriage is blocked by the serial number stamped at the end of the ways.  Mine doesn't have that and I can't see anything that is blocking the exit of the carriage.  Took the opportunity to clean up the leadscrew and apply way oil.

Thank you for your taking time to provide me with all the information and suggestions.  Hope you can also help me with solving the vertical movement of the leadscrew when the half nut is engaged.

Regards,
Wong

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #11 on: January 01, 2012, 10:44:50 PM »
You really should be using a proper way oil. It also helps to flush out chips etc. Grease will retain that contamination. Your slides will also work much smoother with a proper way oil. That's a fine and high quality lathe. It would be a shame to wear it out faster than nessisary.

Pete

Thanks Pete. Since I'm not done with adjusting the lathe, I'll clean up the grease and apply the way oil I bought from A2ZCNC.

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #12 on: January 01, 2012, 11:26:44 PM »
An update.

I bite the bullet and remove the lathe from the chip tray and flip the lathe over.  The 2 setscrews and 2 bolts holding the plate are rather tight. I break the grip of the bolts and setscrews and retightened them.

Now the carriage and leadscrew handwheels turn very smoothly.  I'll do some test cut after lunch with my parents to see if its too loose.

Thank you all for your suggestions and input.  I'm sure I'll have more questions on using the lathe.

Regards,
Wong

Offline andyf

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #13 on: January 02, 2012, 04:09:37 AM »

Hi Wong,

Good to hear you have got it working better.  :thumbup:

Don't worry about the size of the capscrews which lock up the slides. They look no smaller than the gib adjusters, and it needs very little pressure at one point on on a gib strip to lock up a slide completely.

It does seem that there might be some vertical misalignment between the half nuts and  leadscrew. The effect of this will make the leadscrew harder to turn as the half nuts approach the bearing blocks at each end. There is probably of no way of moving the lever, shaft and cam cam which operate the nuts up and down. That leaves two ways of getting things right. First, the fixing holes for the bearing blocks may be slotted, so the whole leadscrew can be lowered slightly. Secondly, you could fit a shim between the apron and the saddle (but then the carriage handwheel pinion should be raised up a little to maintain proper mesh with the rack).

If you can't work out a solution, it might be best to email Proxxon to find out what they suggest.

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #14 on: January 02, 2012, 05:09:42 AM »
Hi Andy,

I'm able to crank using the black handle at the end of the handwheels on both the carriage and the leadscrew from the tailstock end to the chuck end.  Maybe the saddle plate is a little on the loose side that this is possible with the vertical movement in the leadscrew.

I dropped Proxxon an email last night.  Hope to hear from them when their office opens.  They do not have a support email available by the way. Best is, the exploded diagrams at the back of the manual are all in German...

I've bought the article from mini-lathe.com on modifying the saddle so that adjustments can be made from the top than to have to flip the lathe over everytime when need arises.  Ran through the article once and saw that there are 2 gib plates underneath whereas the Proxxon has only 1.  I'm also still try to figure out how to remove the carriage from the ways to help me understand how things work.  So far has no success.

May I know how to read the table on the lathe on suggested feed and speed?  I want to test cut a piece of steel with diameter of 8.35mm.  Any suggestion on depth of cut for machine of this size to start me off?



Thank you once again.

Regards,
Wong

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #15 on: January 02, 2012, 05:23:20 AM »
Hi Graham and Andy,

Shortly after I posted my reply to Andy, I received an email from Proxxon.  The export manager said that the possible cause is the alignment of the "toothed rack".  I was asked to loosen the 4 screws holding them and push them up against the top of the holes tightening them from left to right.

I'm going to try them later and tightened up the gib plate if this was in fact the problem (rather than the gib plate).

Will report back.

Regards,
Wong

Offline andyf

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #16 on: January 02, 2012, 06:26:34 AM »
Hi Wong,

At the top, there is a short list of materials and  the recommended surface speeds in metres per minute for each of them. "Messing" brass. "Stahl" is steel, and I assume it refers to mild steel. I think "Automatenstahl" is free-cutting mild steel.
The table is there to as a guide to show what surface speed per minute your available spindle rpm (shown across the top of the table) will produce on different diameters of stock. You are looking at 8.35mm diameter, and if it is mild steel you want 20 - 40 metres per minute. The nearest diameter shown down the left side is 10mm, and looking across that row it seems that a spindle speed of 1400rpm will give you 44 m/minute. That's a bit fast, but your stock is only 83.5% of 10mm, so its surface speed will be about 83.5% of 44 m/minute - around 37 m/minute. And as you take successive cuts, the diameter and hence the surface speed will reduce.

As to depth of cut, I would start off at 0.25mm for a roughing cut.  That will reduce the diameter by 0.5mm. Bear in mind that the cross-slide may be marked up in "diameter reduction" rather than depth of cut, so advancing 0.5mm as shown on the dial gives you 0.25mm depth of cut.

Experience will show how adventurous you can be with depth of cut. On my 7x12 lathe (which is more robust than the usual mini-lathes) I usually use 0.5mm on mild steel, reducing the diameter by 1mm per pass. I only tend to use cutting fluid near the end, and for light finishing cuts. The feedscrew is 1mm pitch, so on repeated passes I just advance the handle 180 degrees from its previous position. That's easier than reading the dial.

Andy 
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline grayone

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #17 on: January 02, 2012, 02:45:23 PM »
"I think "Automatenstahl" is free-cutting mild steel" - the literal translation is cutting steel so I think it is closer to silver steel which is why the spped probably drops..

Hi Wong the export manager is quite a helpful guy.  Secondly I would not recomend making and serious mods to the lathe at this stage as I am sure adjustments once set up are far and few between.

This is actually one tough machine so don't be too frigtened of it, the best advice I have been given is to listen to the machine and it will tell you what it does not like.  To start with keep the speed down, you won't great a great finish that will come as you play around.  Experiment with the depth of cut, starting out light and working up.  I would also start of with a bit of steel a bit thicker that 3/8th as you will reduce that to swarf very fast :bugeye:.  In passing the dials are direct reading, if you put on 1mm of cut it will reduce the diameter by 2mm and at low spped it will.

Graham
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Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #18 on: January 02, 2012, 04:56:18 PM »
Thanks for the input, guys. Very helpful to start things off with them.

I started with the 8.35mm unknown steel rod as this is the only few pieces lying around that no reversing of chuck jaw is required. When I was experimenting with brass, I changed the power feed gear to 0.14mm/min, which gives a nice finish. The steel rod seems rather tough, the finishing was rough at that feed. Spindle speed was set to 1400rpm. Will test with slower feed and than slower speed to see the effect.

I also noticed that with the steel rod extending out from the chuck about 150mm with tailstock support, I get a turn of 0.02mm.  Is this error considered big? When test on the 20mm dia brass extended out by only 30mm, I have same measurements at both ends (as far as my Mitutoyo digital venier caliper can measure).

Regards,
Wong

Offline grayone

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #19 on: January 03, 2012, 12:50:14 AM »
I also noticed that with the steel rod extending out from the chuck about 150mm with tailstock support, I get a turn of 0.02mm.  Is this error considered big? When test on the 20mm dia brass extended out by only 30mm, I have same measurements at both ends (as far as my Mitutoyo digital venier caliper can measure).

Hi Wong, not quite sure I understand but are you saying that on the steel rod you turned the tailstock end was 0.02mm smaller than the headstock end?  In otherwords it has a long shallow taper.  If so did you use the revolving centre or the fixed on the support the end?  The revolving centre may have a very small amount of play in the bearings which could lead to the effect you have.  If you used the fixed centre then perhaps you need to check that the tailstock barrel is clean and the tailstock itself is also not sitting on a bit of dirt on the ways.

I'm not sure what the limits of accuracy should be between centres as Proxxon onky give for the run-out of the spindle at better than 5/1,000th of a mm.  To test properly what run-out you are getting from headstock to tail you would need to set a long bar between centers and then run a light cut from end to end and then mic both ends.

Graham
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Offline andyf

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #20 on: January 03, 2012, 05:27:09 PM »
Hi Wong,

Speaking personally, I would not be too unhappy with a taper 0.02mm (under 0.001")  over 150mm (6").  But I'm easily satisfied!

Like Graham says, it could be due to a tiny amount of play in the revolving centre, if you used one.

Did you use the 3-jaw chuck which comes as standard with the lathe? Nearly all 3-jaw chucks display some runout, often varying with the diameter of work being held. That would tend to produce a taper with its smaller end near the chuck. If that is the cause, I think most folk would be satisfied with a 3-jaw chuck which had such a small amount of runout.

Graham's suggestion of a test cut between centres would avoid any errors introduced by the chuck.

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #21 on: January 04, 2012, 04:03:56 AM »
Hi guys,

My replies were lost for whatever reason.

The smaller portion is at the headstock end. Further tests were done on steel stock of 25mm diameter with 50mm sticking out of the chuck. I've 0.02mm smaller at headstock.

The next piece was 9.5mm of unknown steel again, this time supportrd by revolving centre. I've the same 0.02mm but it widened to 0.06mm as the stock was reduced to less than 8.5mm. Total length of stock was 150mm, of which 100mm was turned.

One other thing I notice; at 0.25mm depth of cut, 1400 rpm for the thinner stock and 330 rpm for the 25mm. Cutting noise was terribly loud. Up to 0.2mm was ok. I wanted to try greater depth of to 0.5mm but have no courage to proceed fearing that something bad may happen.

Regards,
Wong

Offline andyf

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #22 on: January 04, 2012, 05:17:42 AM »
Hi Wong,

Inaccuracy in the chuck and slight play in the revolving centre will both produce the same effect – the stock will taper down towards the headstock.

As to the noise when you increase the depth of cut, your “unknown steel” could be the problem. Also, you haven’t told us whether you are using a carbide or HSS cutter. Looking at the cutting speeds in the chart you showed earlier, they are for HSS.

Obviously, a blunt tool will cause problems. So will one which has been ground to the wrong angles. The cutting edge should be on centre height, or 3 or 4 degrees above it, but in that case the angle will increase as you take successive cuts, so adjustment may be needed as you go on.

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline wongster

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #23 on: January 04, 2012, 05:33:57 AM »
Hi Andy,

I'm using carbide insert tool.  Tried HSS, didn't like the finishes. Maybe I'm doing it wrong.

Regards,
Wong

Offline andyf

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Re: Hard to crank handwheels - Proxxon PD400
« Reply #24 on: January 04, 2012, 07:35:05 AM »
I rarely use carbide, Wong, so can't offer any suggestions, other than saying that speeds recommended for carbide are often four or five times faster than for HSS.

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short