Member postings for oldvelo

When someone posts a question on MEW and I answer with how something actualy works and go into some details to explain it.

Then they repost my explanation in full then tell me it does not work like that at all. That they have a Theory of the way that they Assume it works is correct and is the only way to solve the problem.

The ones who drift off to post on something that maybe remote and possibly connected the subject being discussed on the forum

Hi

Lets put all contradicting assumptions to one side they are the basis for misunderstanding and cause for many major disasters.

The plan in mind is to deal in facts only and avert such happenings.

The 5 mm 10 mm backlash that you demonstrate in the video is explained in my posting 1) to 5) Which is easily moved by light finger pressure this also allows a cutter that has not had the excessive lead backed off to drag the head down when machining Cast Iron, Bronze, or Brass.

The Worm Wheel does actually turn slightly as the clearances are taken up in this order 1) 5) 4) 3) 2) with a single start worm it is normaly self sustaining.

Perhaps the answer "using gravity to advantge" would be to add a 5kg-8kg weight to the cutting head to take out all the backlash when the head is being lowered and remove the weight when you need to raise the head.

Eric

Hi

"As it stands, it’s just wrong to have the head forced up by default. It must be detrimental to accurate work - if you have a hand feed lever, you intuitively assume it’s limiting the tool position downwards. Currently, it’s basically moving the tool to its highest limit - all bets are off in terms of where it could end up in the workpiece".

"intuitively assume" are not terms consistent with precission engineering. To hold the head from being pulled into the job and elliminate the effect of the backlash is with a higher spring pressure to have the head held firmly UP at all times.

1 ) Backlash in an X2 is the clearance in the Rack and Pinion

2 ) The clearance in the Worm and Worm Wheel

3 ) End float on the worm to housing

4 ) Clearance on the Teeth on the Dog Clutch

5 ) Clearance on the Key and Keyway on the Pinion Shaft in The Dog Clutch

6 ) Two Universal Joints on the Worm Shaft Drive

All adds up to an excessive ammount of backlash. Around 3/4 of a full turn on my reasonably adjusted machine.

Eric

Hi

A lot of solutions quoted until you address this the problem will continue

( I’m not using modified tools, they are standard mills, drills or slot drills. I wouldn’t know how to modify them anyway)

Higher rated Air spring will give higher resistance to the cutter being dragged into the softer metals by the cutter edge angle and maintain pressure taking out any backlash.

The cutter can be modified with a Dremel grinder and back off the cutting edge to parallel to the Centre Line.

Eric

Hi

The gas strut needs enough power to push the head up to the top with with the fine feed disengaged and the lock slackened off.

Fit "Air Spring" to counter weight of mill head 24 kg rated is the one I have fitted to a much modified X2 mill.

If the castings you are spot facing is Çast Iron, Bronze, or Brass you need an end mill with the cutting edges backed off to 90deg to prevent the end mill from diving into the castings. The piddly little hand wheel is a pain to use the photo shows the mods done on X2 Mill Drill

Eric

Hi Woody

The toothed belt runs smoothly when tensioned correctly and should cause no problems.

The gibs on the top slide and crossslide may require some attention to get better performance to the finish.

One mod I have done is to replace the adjuster screws with cup point socket head grub screws and a 4mm ball bearing to look like this " <o> " Lock up the gibs tight then remove one and with a 4mm drill in an eggbeater hand drill tidy up the dimple in the gib strip. Put ball in and tighten up the grub screw then repeat with the next adjuster screw.

Eric

Hi Woody

General opinion for bearing is to replace with angular contact ball bearings. These are the same dimensions as the original bearings.

The toothed belt on low speed will give positive drive. Vee Belts do not perform well at low speeds and high loads and tend to slip.

An option is to use poly vee belts "J" section 4 ribs or overkill with 6 ribs is adequate for 300 watt motor.

Simple enough to fabricate pulleys from Aluminium or Cast Iron Keep the diameters the same as the original or propotionally bigger that will still fit under the guards.

Poly Vee belts perform quite well at low speed compared to vee belts.

Eric

Hi

Pete says "Many good lathes fitted with variable speed have also been fitted with a tacho or speed readout." mine is only mediocre and has one fitted. Mill and Drilling machine share at the flick of a switch.

Variable speed power feed is also a good option. An Amp meter fitted to the main motor leads will help keep from overload when using a heavy cut.

Eric

Xd 351 points out the gap under the toolpost as the most probable cause. High speed steel ground for cast iron needs negative rake and the tip set not lower than centre hieght. Honing a high speed steel insert with an oil stone for better finish on almost all metals.

Eric

Hi Peter

please make sure that the controller is set up to match the motor. John will be able to help you with this task

Eric

One size that defies the use of metric or AF substitute is 5/16 Whit Post war.

Hi Apologies to all for wrong link

Eric

Hi David

Keep us posted on your lathe motor repairs alway intrested in how thing get fixed.

Eric

Hi David

Ouch! sound expensive. The use of the low speed recomended with the motor running at higher speed.

One improvement I have posted repeatedly is to fit a DC Ampmeter on the motor leads.

Mark the Guage with Motor Max Amps.and adust the cutting load to a reading of less the Motor Amperage.

Posted elsewhere Amp Meter

Eric

Hi

An Ampmeter on the motor leads to monitor motor current to prevent overloading is a useful addition

Eric

Hi Dave

Try this Link for Electronic DC Controls A great library of mauals is available at the bottom of the KB's Page

KB Electronics Or Minarik Minarik DC Motor Control Or Dart Dart DC Motor Control

I bought units and motors from Factory surplus spares sales for a fraction of the cost of new units.

Read and Enjoy Eric

Hi Dave

Welcome

I can speak from experience and with no connection to any company.

My workshop is powered by DC brush motors with American built AC to DC speed controllers form Dart, Minarik, KB Electronics.

With your background it will be no trouble for you to set up the controller to the motor.

Not the cheapest options available but reliable as to be able to set and forget.

Eric

The minimum diameter will depend on the material you wish to bend. Working in a jobbing shop we rolled everything from Armour Plate a total pig to anything less than 5 times the roll diameter to soft brass that was 1.25 the roll diameter was quite easy to achieve.

For up to 8 mm round stock you can use the spring makers method and wrap the on a mandrel in the lathe with snubber block in the toolpost.

Eric

Saw a while back a photo of a whole lot of cap on back to front brigade at a motor race meeting in late afternoon sunshine holding up a hand to shade their eyes. Explains a lot.

Eric

Hi John

With My very limited knowledge is thatThe Myford Speed 10 has taper roller bearings.

Is the preload on the Taper Roller Bearings set correctly.

On a used machine with overheated bearings is most probably over greasing.

A quick dismantle of the of the rear bearing with the inner race removed, cleaned, inspected the inner race for any damage. Reassemble with fresh grease not more than 1/4 of the total bearing housing.

Reset the bearing preload after running and allowed to cool down to room temprature.

Afterthought edit! When a new bearing is fitted they will often run hot when run at high speed until they are "run in" 

Eric

Edited By oldvelo on 15/08/2020 00:59:38