Draper MD350 Naerok RDM350 New Owner Questions

[Howard LewisParticipant @howardlewis46836]

My Mill/Drill, is an RF25, if that is any help, and the laser mounts in a slot on a custom made bracket on the front of the head, backing up to the casting.

The laser was a B&Q cheapie, about £7.99 from memory.

I had my doubts, but when Stan Bray said “About a thou”, I believed him, and took the risk.

Howard

[Howard LewisParticipant @howardlewis46836]

My Mill/Drill, is an RF25, if that is any help, and the laser mounts in a slot on a custom made bracket on the front of the head, backing up to the casting, so a short distance ahead of the spindle centreline.

The laser was a B&Q cheapie, about £7.99 from memory, which produces a slightly non parallel line, to which the target was aligned, for subsequent use.

I had my doubts, but when Stan Bray said “Within a thou”, I believed him, and took the risk.

He appears to have been correct.

Howard

[Howard Lewis]

On Howard Lewis Said:

My Mill/Drill, is an RF25, if that is any help, and the laser mounts in a slot on a custom made bracket on the front of the head, backing up to the casting, so a short distance ahead of the spindle centreline.

The laser was a B&Q cheapie, about £7.99 from memory, which produces a slightly non parallel line, to which the target was aligned, for subsequent use.

I had my doubts, but when Stan Bray said “Within a thou”, I believed him, and took the risk.

He appears to have been correct.

Howard

Model number doesn’t mean a thing to me, Howard … but I’m sure I can look it up.

I see now that you are using a line, not a spot

… I am genuinely happy that it is all working nicely for you.

MichaelG.

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P.S. __ this is somewhat  ‘heavier’ than the Edmund Optics one that I posted earlier, but may be of interest to some:

https://www.thorlabs.com/images/TabImages/Elliptical_Beam_Circularization_Lab_Fact.pdf

[Michael GilliganParticipant @michaelgilligan61133]

Having located an RF-25 manual … it appears that the number I was was querying [which RF calls swing] is 404mm, or 15 7/8”

I can do my silly sums now

MichaelG

[Michael GilliganParticipant @michaelgilligan61133]

This is quick&dirty but it appears to work

The example values displayed relate to the RF-25 and Howard’s set-up, expressed in Inches … but any set of consistent values should work.

The calculated result is the positioning accuracy we need to have at the target, to achieve the required positioning accuracy at the workpiece.

B8 = (B6/B2)xB4

My offering is totally uncontentious … it’s just sums

What any individual can achieve, with whatever configuration is used, is really the only unknown.

MichaelG.

.

 

[Martin ConnellyParticipant @martinconnelly55370]

As a matter of interest, how easy is it to tighten the clamping of the head to the round column without it moving slightly? Do you have to make allowances for it moving before tightening? Since the small electronic probes can reacquire a position to 0.01mm (my own checks) any error above this using a laser would make the laser less accurate.

Martin C

[Howard LewisParticipant @howardlewis46836]

The RF25 was imported by by a number of British companies. Mine is badged as a WARCO Economy.

Have just been out and done a quick and nasty dimension check.

Using the angular error in positioning the head, the linear positional error of the spindle centre can be calculated

Column diameter, 3.6″ (Probably not 248.92 mm but maybe 250mm. But with a machine of that vintage having linear graduations, and some Imperial threads, you never know)

Column to spindle centre 8″

So column centre to spindle centre = 9.8 ”

Taking the angular error as having been calculated previously as 1.7 minutes of arc, (And working as 1.7 degrees, for the moment, to make life easy)

Tan 1.7 = x / 9.8, so x = 9.8*Tan 1.7 = 9.8(0.02679307)

x = 0.290857209 / 60 (To convert from degrees to minutes) = 0.048762* 10^-3

Which looks like just less than 0.0005″ to me

Even if the laser beam is 0.125″ wide, and is read with that degree of error, the late Stan Bray’s estimate of “within a thou”, is valid.

Howard

[Howard Lewis]

On Howard Lewis Said:

The RF25 was imported by by a number of British companies. Mine is badged as a WARCO Economy.

Have just been out and done a quick and nasty dimension check.

Using the angular error in positioning the head, the linear positional error of the spindle centre can be calculated

Column diameter, 3.6″ (Probably not 248.92 mm but maybe 250mm. […]

I must have looked at the Wrong Rong Fu then !

https://www.scribd.com/doc/186564027/Rong-Fu-RF-25-Mill-Manual

 

… I will say no more … my input is evidently noise

Be Happy

MichaelG.

[Russell TalbotParticipant @russelltalbot34770]

Thanks for all the comments and advice to date.

I have done one of the jobs that was quite strongly recommended and I’ve fitted a DRO.  This took longer than I expected as I didn’t want to lose any travel, or to lose the use of the table stops or clamps on the x-axis or the quill stop on the z-axis.

I was also delayed by having to do the x-axis twice as although I’d carefully checked that the scale fitted, I had overlooked that the cable wanted to go through the same space as the table clamp and I had to move the scale up a few millimetres.

The scales are the common Chinese glass scales and the DRO is a home built TouchDRO using an android tablet as the display.  I’ve also added an infra red sensor under the top pulley to measure the revs.  That has allowed me to see what the actual speeds are in spite of the missing sticker.  I was a bit surprised to see there is quite a big gap in the speed range.  Available speeds are 110, 198, 220, 352, 390, 402, 909, 1250 and 1792. The DRO also has an input for a probe – I’m still thinking about exactly what sort of probe to use.

Tidying and clipping cables is next on my list.

The manufacturers recommend covering the scales with a guard against chips, dirt and coolant and I’m unsure what to do.  I think I will add a cover to the Y-axis scale – mainly to protect it against being hit accidentally with the clamp handles at the base of the column.

I’m fairly sure the z-axis will be fine.

The one I am unsure about is the x axis – I can’t think of a neat way to fit a guard without making it difficult to get at the table stops or clamps or both.

The table stops can be clamped in place using a small screwdriver or an allen key in the special bolts behind the scale as seen in this photo.

I’m not intending to use coolant and it is not going to be a heavily used machine – I’m inclined not to bother with a guard on that scale – what does anyone else think?

Does anyone have an opinion on the benefits (or otherwise) of covers on the ways?

Russell

 

[DiogenesParticipant @diogenes]

I said goodbye to the stops when I got the DRO and used the slot to hold the scale.

I do use a cover, thinking that it helps keep c**p away from the read-head / scale interface, lessens risk of damage from dropped spanners / drawbars, and acts as a mount for P/F knock-offs.

I have a piece of rubber sheet to catch swarf before it reaches the shears and screw at the back of the table, however I haven’t always done so – it’s just surprising how quickly a bit of milling will create a mountain of chips that you will have to move, esp. because you’ll want to keep the screw and ways lubricated – it just becomes a bit of an unpleasant chore & sooner or later some small part / drill bit will fall down there..

 

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